MINERALOGICAL CHEMISTRY.THE year 1912 has not been productive of any remarkable advancesin the field of pure Mineralogy. A number of new minerals havebeen dmcribed, but few of them can be regarded as species of anygreat interest or importance; and although many analyses of well-known minerals have been published, the majority of these havebeen made for purposes of identification, and have thrown but littlelight on vexed questions of mineral composition with the notableexception of the work on tourmaline and nephelite, which we oweto American investigators.On the other hand, in the domain of theory, speculation has beenrife, and we shall have to notice some interesting suggestions as tothe possible constitution of the silicates.In the borderland where Chemistry, Physics, and Mineralogymeet considerable activity has prevailed ; thus the investigation ofbinary mixtures by thermal methods has attracted many workers,and some very important attempts to elucidate mineral formationhave been successfully carried out by synthetical methods in theGeophysical Laboratory a t Washington.I n the domain of chemical crystallography, Fedoroff has provedthat the system of classification a t which he has laboured so per-sistently affords us the means of readily identifying by its crystalform alone, any substance of which measurements have beenrecorded.Lastly, we must not omit to call attention to the publicationby the German Mineralogical Society of volume I1 of their usefulsummary entitled (‘ Fortschritte der Mineralogie, Kristallographieund Petrographie.”We will now proceed to a brief survey of the progress made inthese various directions, and will follow in the main the method oftreatment adopted in previous years.General and Physical Chemistry of Minerah.Silicate Fusions.-There has been an increasing tendency of lateto apply thermal methods to the study of many systems other than25256 ANNUAL REPORTS ON THE PROGRESS QF CHEMISTRY.those composed of silicates, and this is perhaps the reason why thereare this year but few researches in the silicate group which call forspecial comment.Among the most important of these is aninvestigation into the mutual relations of the compoundsCaAI,Si,O, and Na,AI,S~O,, carried out in the Geophysical Labora-tory a t Washington.1 It has already been shown that the former,anorthite, can readily be synthesised by fusing together calciumcarbonate, alumina, and silica.It has now been ascertained thatthe latter exists in two crystalline forms; one stable a t temperaturesbelow 1248O (about) is hexagonal, and may be termed soda-nephelite; the other, or higher temperature form, is anorthic, andis called soda-anorthite or carnegieite.Both forms can be obtained by fusing together sodium carbonate,alumina, and silica in the proper proportions, care being taken toavoid loss of soda by too vigorous heating, for if this occurs, crystalsof corundum appear in the product. Neither of these substanceshas been found in nature, although they enter into the compositionof nephelite and of certain plagioclase felspars.Crystals of soda-nephelite sufficiently large for study were obtained by crystallisa-tion from sodium tungstate. On studying the cooling curves andthe products obtained by quenching various mixtures of thesecompounds after they had been heated to definite temperatures fora sufficient length of time, it was found that soda-nephelite andanorthite form mixed crystals with a maximum content of 35 percent. of the latter substance, corresponding with the presence of7 per cent. of lime. Carnegieite, on the other hand, will only takeup at the most 5 per cent. of anorthite. As the proportion ofanorthite increases the birefringence of the nephelite diminishes,and when 23 per cent. of anorthite has been added the originallynegative crystals become isotropic, On further addition of anorthitethe crystals become positive.An investigation into the nature of Portland-cement clinker,involving the study of the ternary system limealumina-dica, wasreferred t o last year.In the course of the work evidence wasobtained which went to show that 8CaO,A1,O3,2Si0,, the ternarycompound obtained by Janecke, was really a mixture.2 The latter,however, states that melts of the above composition show a verysharp arrest on the cooling curve, and that under the microscopethin sections of the product are seen to consist of perfectly uniformcrystals with only small enclosures of glass.8A certain number of fusion experiments have also been made onN.L. Bowen, Amer. J. Sci., 1912, [iv], 33, 551; A., ii, 774.G. A. Rankin and F. E. Wright, Zeitsch. anorg. Chm., 1912, 75, 63 ; A . , ii,E. Jamecke, ibid., 76, 357 ; A., ii, 761.554MINERALOGICAL CHEMISTRY. 257natural minerals4; thus olivine (m. p. 1600°) and diopside (m. p.1363O) gave a eutectic a t 1271O containing 40 mol. per cent. ofolivine. Wollastonite and anorthite gave a eutectic containing30 mol. per cent. anorthite a t 1285O. Aegirite and anorthite gavea plagioclase f elspar intermediate between andesite and labradorite,together with the original components.A number of binary mixtures of meta-silicates of calcium, mag-nesium, iron, and manganese, both natural and artificial, have alsobeen examined, and the opt.ica1 properties of the solidified meltsdescribed in detail.5 The products include rhombic pyroxenes,diopside, choenstatite, wollastonite, and hexagonal calcium silicate.The work of Cooper, Shaw, and Loomis on the binary systemsilica-lead cxide, established the existence of the compoundsZPbO,SiO, and PbO,SiO,, and evidence was also obtained by others 6of the probable existence of 3Pb0,2Si02 and 3PbO,SiO,.Cooper,Kraus, and Klein7 have confirmed the presence of the first threecompounds in the melts, and have shown that the optical propertiesof the second and third are identical with those of the mineralsalamosite 8 and barysilite respectively.S d p h i d e Fusions.-A number of binary systems composed ofsulphides have also been subjected to thermal analysis.From themineralogical point of view the results obtained by F. M. Jaegerand H. S. van Kloosterg in their study of the thioantimonites andthioarsenites are perhaps the most important. When antimony andsulphur are melted together the only compound produced is Sb,S,,corresponding with a maximum on the freezing-point curve a t 546O.There are eutectic points a t 530° and 519O, corresponding with 61.3and 55 atomic per cent. of sulphur respectively. Mixtures of Sb,S,and Ag,S (m. p. 842O) give a freezing-point curve with two maximacorresponding with 3Ag2S,SbzS3, pyrargyrite (m. p. 483O), andAg,S,Sb,S,, miargyrite (m. p. 509O). Eutectics are found at 463”,455O, and 449O corresponding with 81, 64.5, and 28.2 mol. per cent.of Ages respectively.The minerals bolivianite, stephanite, pyro-stilpnite, polybasite, and polyargyrite are not represented in thethermal diagram, and have probably been formed from solution.The system Ag2S-As,S3 gives similar results, the compoundsformed being 3Ag,S,As,S3, proustite (m. p. 490°), and Ag,S,As,S,(m. p. 417O). Mixtures of artificial proust.ite and pyrargyrite form4 P. Lebedeff, Ann. Inst. Polytechn. St. Petersburg, 1911, I, 15, 691 ; A . , ii, 919.G. Zinke, JaArb. Min., 1911, ii, 117 ; A., ii, 359.Ann. Report, 1910, 227.7 H. C. Cooper, E. H. Kraus, and A. A. Tilein, A m r . Chem. J., 1912, 47, 273 ;8 Ann. RepoTt, 1909, 221.9 Zcifsch. anorg. Chem., 1912, 78, 245 ; A , , ii, 1169.A . , ii, 452. See also Centr. Min., 1912, 289 ; A . , ii, 645.REP.-VOL.IX. 258 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.an unbroken series of solid solutions, a point of considerable interestin view of the fact that the natural minerals only occur mixed to avery limited extent.In the case of the system PbS-Sb2S3 two compounds can berecognised, 5PbS,4Sb2S3, plagionite, and 2PbS,Sb2S3, jamesonite,but there is no evidence for the formation under these conditionsof the minerals zinckenite, warrenite, heretomorphite, semseyite,boulangerite, meneghinite, or geocronib.Similar investigations have been made of the binary systemsCu2S-Sb2S3, SnS-Sb2S3,fo and PbS-SnS.11 The former gives rise totwo compounds Cu2S, Sb2S3, corresponding with chalcostibite, and3Cu2S,Sb2S3, the main constituent of stylotypite. In the case ofthe second system the compound SnS,Sb2S3 is probably formed. Thethird system gives two series of solid solutions extending from0 to 8 per cent.SnS, and from 38-7 to 100 per cent. SnS. The existcence of a compound, SnS,PbS, although probable, has not beendefinitely established.A certain number of systems involving sulphides and other com-pounds has also been investigated; thus Quercigh12 has found thatSb,03 and Sb,S3 are miscible in all proportions in the molten state.A compound, 5Sb,S3,Sb203, is formed, which, however, does notmelt unchanged, but decomposes a t 522O into Sb2S, and a liquidphase. It gives a eutectic with Sb203, which has the composition ofthe mineral lcermesite, 2Sb2S,,Sb203. It would appear, therefore,that the latter cannot be obtained from fused mixtures of its com-ponents.The behaviour of the sulphide-chloride systems ofsilver,13 lead, and copper14 has also been investigated, and it hasbeen shown that the oxides of tin, zinc, lead, and copper, and thesulphides of the three latter metals are appreciably soluble inmolten sodium chloride.15Salt Fusions.-A very large number of binary mixtures of haloidshas been examined by various workers,l6 but we need not here domore than refer to certain investigations of binary mixtures ofsulphates of the alkali metals with those of the alkaline earths>'lo I?. Parravaiio aud P. de Cesaris, Gazzetta, 1912, 42, ii, 189 ; A . , ii, 942 ; andAtti Iz. Accad. Lincei, 1912, [Y], 21, i, 535 ; A., ii, 771.W. Heike, Metallurgie, 1912, 9, 313 ; A ., ii, 763.l2 Atti R. Accad. Lincei, 1912, [v], 21, i, 415; A . , ii, 562.l3 C. Sandonnini, ibid., 479 ; A., ii, 759.l P W. Truthe, Zeitsch. anory. Chem., 1912, 76, 161 ; A., ii, 763.l5 H. Houben, Metallurgie, 1912, 9, 592 ; A., ii, 1056.l6 Compare C. Sandonniui, Atti X. Accad. Liacei, 1912, [v], 21, i, 208, 493 ;ii, 77 ; A., ii, 350, 764, 918 ; M. Amadori, ibid., 21, i, 467 ; A . , ii, 758 ; H. Brand,Centr. Min., 1912, 26. Seealso Jahrb. Min. B d . - B d . , 1911, 32, 627 ; A., ii, 255.l7 G. Calcagui, Atti A. Acead. Lincei, 1912, [v], 21, i, 483 ; ii, 71, 240, 284 ;A, ii, 761, 918, 1056MINERALOGICAL CHEMISTRY. 259and to some work on the phosphates of lead.18 Finally, we maymention that a simple method of studying thermal dissociation hasbeen devised by I(.Friedrich,lg and applied by him t o the investi-gation of the dissociation of the carbonates of lead, zinc, iron,manganese, magnesium, calcium, and barium, including those whichoccur as minerals.Constitution of Hydrates and EEydroge1s.-G. TschermakFO incontinuation of his work on the dehydration of the silicic acids, hasmeasured the velocity of dehydration at constant temperature of anumber of hydrated salts. He finds that a well-marked retardationtakes place at certain points during dehydration corresponding withthe abrupt fall in vapour pressure which accompanies the passagefrom one stage of hydration to another. Experiments with sodiumsulphate, barium chloride, sodium phosphate, and strontium hydr-oxide gave good results, and even in the case of zeolites similarretardations were observed.The same holds good for hydrogels,retardation taking place a t certain definite points, and it wouldseem that certain hydroxides are to be regarded as containing waterof crystallisation a t the first retardation point, as, for example,2A1(0H),,H20, whilst others, such as Si(OH),, decompose, and givelower and more stable states of hydration.Constitution of the Silicates.-A work of considerable importancedevoted to this subject has recently appeared,21 but it is impossiblehere to do more than call attention to the nature of the remarkabletheory it sets forth.The silicates are regarded as derived, not from the simple hydr-oxides Si(OH), or Al(OH),, but from compounds formed by con-densation of five or six such molecules t o form respectively a pentiteor hexite group, linkage taking place through oxygen.Thesegroups may themselves be further linked together to form morecomklex groupings. By the replacement of hydroxylic hydrogenby metals, and of hydroxyl by fluorine formula= are obtained for anumber of natural silicates. Although it may be felt that theauthors g o too far when they assign formulae to certain glasees andto some of the products of the Portland-cement industry, yet theirviews deserve careful examination on the part of mineralogicalchemists.Some interesting suggestions as to the formulze of the felspars,leucite, nepheline, the zeolites, and the scapolites, have alsoA.V. M. Kroll, Zeitsch. anorg. Chm., 1912, 78, 95 ; A., ii, 1056.l9 Centr, blin., 1912, 174, 207, 616, 651, 684.2* Monatsh., 1912, 33, 1087 ; A., ii, 1140.21 ‘‘ Die Silicate in chemischer und techniucher Beziehung,” W. Asch and D. As&,Berlin, 1911.s 260 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.been made recently by H. S. Washington.22 He regards theseminerals as derived from two alumino-silicic acids, the first fourbeing obtained from the acid H,AlSi,O,, and the last fromHl,,AlSi3012, the hydrogen of these acids being replaced, not byvariable and independent atoms, but by atomic groups, the totalvalence of which is that of the basic hydrogens.Heats of Solution of Minerah-By the aid of a platinum calori-meter the heat evolved when quartz, alumina, and various silicatesare dissolved in hydrofluoric acid may be determined.23 I n this wayit has been found that the heat of solution of quartz is 29.93 cal.per gram molecule, that of vitreous silica 32.14 cal., and that ofalumina 93.86 cal.The heats of formation of certain crystallinesilicates have also been calculated, with the following results :adularia, 131.2 ; leucite, 101.8 ; microcline, 104.2 ; analcite, 85-22 ;natrolite, 95-76 ; heulandite, 59.44.Special Properties of Certain iKi.nerals.-The following interestingobservations on the solubility in water of calcite and of aragoniteare worthy of notice.? Solutions were made in silica vessels attemperatures of 25", 50°, and looo respectively, with the resultthat a t all three temperatures the solubility of aragonite was foundto be slightly greater than that of calcite, the ratio of the solubili-ties a t the several temperatures remaining, however, practically thesame.The actual solubilities observed expressed in milligrams perlitre are as follows: calcite, 14.33, 15.04, and 17.79; aragonite,15.28, 16.17, and 19.02.On determining the solubility of calcium carbonate got byremoving carbon dioxide from solutions of calcium hydrogencarbonate a t various temperatures, it was found that for theproduct obtained a t 25O the solubility was practically thq same asthat of calcite. The values for the product obtained at looo agreedwith those of aragonite, whilst the product obtained at 50° gaveintermediate results.These observations are in agreement withwhat is known as to the nature of the crystals which separate fromcalcium hydrogen carbonate solution at different temperatures.Some important work has also been done on the behaviour ofcalcium carbonate when heated under pressure in an atmosphereof carbon dioxide.25 By means of an apparatus provided withwindows of silica glass, and which could be filled with gas under apressure of 150 atmospheres and heated to 1600°, it was found thatpure calcite melts without decomposition a t 1289O when heated incarbon dioxide under a pressure of 110 atmospheres. Calcium0. Mulert, Zcitsch. unorg. Chcm., 1912, 75, 198; A., ii, 626.22 Amer. J. Sci., 1912, [iv], %, 555.24 J. Kendall, Phil. Mug., 1912, [vi], 23, 958 ; A., ii, 643.26 H.E. Boeke, Jukrb. Min., 1912, 1, 91 ; A., ii, 760MINERALOGICAL CHEMISTRY. 261carbonate and lime forin a eutectic containing 91 per cent. of theformer substance a t 121S0, but no mixed crystals or intermediatecompounds were observed. The heating curves indicate a changeof calcite into another variety a t 970°, but the optical characterremains unchanged.I n conclusion, we may mention that Meigen’s test for calcite andaragonite based on the colours they give when boiled with cobaltnitrate solution has been examined by Niederstadt,26 and thatVaubel27 has suggested that the differences in the chemicalbehaviour of these two minerals may be explained on the assump-tion that aragonite contains a small quantity of a basic carbonate.Chemical Crystallography.The most important matter to be dealt with in this section ofour report is the remarkable achievement of Fedoroff,28 who hasbrought to a successful issue the stupendous task of reducing to aform available for purposes of reference the chaotic mass of dataconcerning crystal form collected during the past hundred years.Since the days of Hauy and Mitscherlich chemists have been wellacquainted with the fact that all crystals of the same substance,even if they have been grown under different conditions and possessapparently very different shapes, can always be referred to the sameset of crystallographic constants, characteristic of the substance,except in those cases where the difference in form is due to poly-morphism, that is, t o the existence of two or more distinct varietiesof the substance.Again, it has been shown that even in the caseof isomorphous substances the angles almost invariably differ bymeasurable amounts unless they belong to the cubic system.Kow since the crystalline form is a highly characteristic propertyof a chemical compound, and as, moreover, it has actually beendetermined in the case of more than 10,000 substances, it wouldseem reasonable to suppose that the study of crystal form wouldafford a very valuable means of identification. To a certain limitedextent this expectation has been realised, for it has generally beenpossible to decide, without much difficulty, whether a certainsubstance A, produced in a chemical reaction, was identical witha known substance B, or not.I f , however, it happened that A wasproved t o be different from B, and the further question was akedI‘ Is A identical with any one of the 10,000 measured substances ? ”then the inquirer was doomed to disappointment, for until Fedoroff26 K. Niederstadt, Zeitsch. angew. Chem., 1912, 25, 1219 ; A., ii, 760.2i W. Vauhel, J. p r . Chem., 1912, [ii], 86, 366 ; A . , ii, 1180.28 E. S. Fedoroff, Zeitsch. Kryst. Mzh., 1912, 50, 513262 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.undertook the work, no classification of the data existed, and anyattempt a t comparison was a hopeless task.The apparently insuperable difficulty which has hitherto stood inthe way of any useful employment of the existing data is inherentin the fact that a very large number of compounds crystallise inthe orthorhombic, oblique, and anorthic systems.I n these systemsthe values of the crystallographic constants vary enormously withthe “setting,” that is to say, with the particular faces chose‘n asprisms, basal plane, and fundamental pyramid. Now the identityof two crystals for which different settings have been adopted canonly be established by a highly laborious comparison of angles, andthe task may be further complicated by the fact that the habit,that; is to say, the particular faces present and their relativedevelopment, may often differ greatly if the crystals have beendeposited from different solutions.The first and most important step, then, is to lay down somegeneral principles upon which to decide the choice of the particularsetting to be adopted, and thus to insure uniformity of treatmenton the part of different crystallographers measuring crystals of thesame substance produced in different ways, The great achievementof Fedoroff is that he has succeeded in developing the necessaryrules on the sound basis of the theory of crystal structure he hasdone so much to perfect.Granted, however, that the correctsetting has been ascertained, much remains to be done, and here,too, Fedoroff has succeeded in establishing order out of chaos.I n the general case presented by the anorthic system five inde-pendent angles are necessary for a complete determination of theform, and of the measured angles the following were selected fortabulation; the angle between the two prism faces, the two anglesthat these make with the basal plane, the angle from the base on tothe most important pyramid plane, and, lastly, the angle of thelatter with one of the two prisms.An index was next prepared ofthe 10,000 substances, arranged according to their systems, andaccording to the values of the above angles. To identify anunlabelled specimen of any one of these substances is now a fairlyeasy task. The crystals are measured, preferably, although notnecessarily, on a two-circle goniometer, the system is determined,the correct setting ascertained, and the characteristic angles eithermeasured, or calculated from other angles. The index is thensearched, the whole process occupying on an average not morethan two hours.The index, although complete, has not as yet been published,but when it becomes available, and crystallographers havemastered the principles which determine the correct setting, iMINERALOGICAL CHEMISTRY.263will no doubt be of immense and ever-increasing value to thechemist. The more, indeed, the chemist and the crystallographercan co-operate, or better, perhaps, be combined in the same person,the greater will be the benefits which may be expected to accrueto the workers in organic chemistry, to whom an easy, but sure andtolerably rapid method of identification is of first-rate importance.That the classification devised by Fedoroff really does what heclaims for it has been demonstrated beyond cavil by the successwith which he identified forty-eight out of fifty unlabelled speci-mens sent t o him from this country.Of the remaining two, onehad not been previously measured, and therefore was not in hisindex, and the crystals of the other were not sufficiently developedfor complete determination.It is, of course, obvious that cubic substances, which, after all,are not very numerous, are not amenable t o this mode of treatment,nor does it in most cases differentiate between the members of anisomorphous series. I n the latter case, however, the type oncedetermined, it is easy to identify the individual by other methods.Fedoroff’s work has been concerned with the co-ordination ofexisting data, but we have also to chronicle some important contri-butions to our knowledge of the crystallographic relations of groupsof analogous substances ; thus the morphology and optical charactersof the double chromates of caesium, rubidium, and ammonium withmagnesium chromate have been the subject of exhaustive study,29and it has been found that rubidium magnesium chromate andcaesium magnesium chromate exhibit crystal characters preciselysimilar in their mutual relations to those of the rubidium andmsium salts of every group of double sulphates and selenatesalready studied, whilst the position of the ammonium salt in themagnesium group is similar to that found in general for theammonium salt of any group of double sulphates or selenates ofthe series.In the field of organic chemistry, H.E. Armstrong and E. H.Rodd 30 have continued their studies of salts of p-dibromobenzene-sulphonic acid, and have shown that the lanthanum, neodymium,praseodymium, and cerium salts of this acid crystallise with ninemolecules of water in the orthorhombic system, and form a veryclosely isomorphous series. It will be noticed that the number threeplays a very important part in the economy of them salts, for theynot only each contain three phenyl groups, three sulphonate groups,and three times three water molecules, but they also possess a29 A. E. H. Tutton and Miss M. W. Porter, itfin. Mag,, 1912, 16, 169; A.,ii, 560.av Proc. Roy, Soc., 1912, A, 87, 204 ; A., i, 7562644 ANNUAL REPORTS ON THE PROGRESS OF CHEMISlRY.pseudotrigonal axis.The gadolinium salt with twelve molecules ofwater is oblique, but also possesses a pseudo-trigonal axis, and themorphology of all five compounds can be correlated with that ofp-di-iodobenzene. These facts admit of ready explanation on thePope-Barlow theory of the structure of benzene, the values of theequivalence parameters being exactly what we should expect if thebenzene structure is imagined opened out equally in all directionsperpendicular to the pseudotrigonal axis to a sufficient extent toadmit the insertion of the substituting groups in homogeneous closepacking.Another interesting piece of work has thrown fresh light on themorphotropic relationships which prevail between racemic com-pounds and their optically active components.31 Crystallineexternally compensated substances may occur either as mechanicalmixtures of the dextro- and lzvo-forms, as true racemic compounds,or as pseudo-racemic compounds, the crystals of the latter beingmade up of crystals of the separate optically active forms twinnedtogether. I n this last case the form of the compound crystal mustof necessity bear a very close relation to those of its components,but it has also been shown, that a very close morphotropic relationoften exists between the crystals of a true racemic compound andthose of its dextro- and lzvo-compounds. A particularly strikinginstance has long been known in the case of sobrerol, and to thismay now be added numerous fresh examples, such as racemiccamphoric anhydride, benzoyltetrahydroquinaldine, camphoroxime,the hydrogen racemates of potassium, rubidium, caesium, andammonium and thallium racemate. On calculating the equivalenceparameters in accordance with the Pope-Barlow theory, a very closecorrespondence is observed between the values obtained for theindividual components and for the racemic compound.The crystallographic relations of a number of salts of s-ethane-disulphonic acid have been studied by I(.Bleicher.s2 These includesalts of ammonium, lithium, sodium, potassium, calcium, strontium,barium, magnesium, zinc, cadmium, and copper. It would appearfrom the measurements that the nature of the metal is a minorfactor in determining the form, and it would therefore be ofinterest to know the form of the free acid.Unfortunately, how-ever, this could not be obtained in crystals. It was observed thatthe lithium salts-show greater analogies to the salts of the alkalineearths than with the salts of the alkali metals.This section may be fitly concluded by reference to two importantpapers of a more theoretical nature. We will begin with an31 G. Jerusalem, T., 1912, 101, 1268.32 Zeitsch. Kryslst. Mi?&., 1912, 51, 502MINERALOGICAL CHEMISTRY. 265exhaustive discussion on the part of C. Hlawatschs of the variousviews which have been held as to the nature of isomorphism. Thegeneral outcome of this discussion is i19 follows: I n the first place,i t is desirable to consider separately the three conditions usuallyconsidered necessary for isomorphism, namely, that two differentsubstances should (1) have similar crystal form, (2) have analogouschemical composition, (3) form homogeneous mixed crystals.I n thestrictest sense of the word all substances which fulfil the first condi-tion are isomorphous. As, however, the external form is merely theexpression of internal structure, we may say that those crystallinesubstances are isomorphous whose structure is analogous. Since theformation of mixed crystals and parallel growths is conditioned orassisted by analogy of structure, these phenomena afford indicationsof the existence of isomorphism. Since, moreover, similarity ofchemical composition will often result in analogy of structure, it isplain that isomorphous substances will often exhibit close chemicalanalogy.It is, however, quite possible for substances of verydifferent chemical composition t o have the same structure, and insuch cases we must be on our guard lest we seek to establishchemical relations where none as a. matter of fact exist. The forma-tion of mixed crystals cannot be regarded as an all-sufficient condi-tion for isomorphism, as the number of cases of their formation bysubstances of very different form is continually increasing.It urould seem possible, however, to classify substances accordingto their degree of isomorphism on the lines of the followingscheme :(1) The substances exhibit no chemical analogy, but show simi-larities in certain zones which frequently grow parallel.(2) The substances show analogies in their angles, but do notexhibit the same cleavages or habit.This may be termed isogonism.(3) The substances form mixed crystals, but have not analogousstructure.(4) The last case is not to be confused with that presented byisopolymorphous substances when the two modifications possess verydifferent stability.(5) The substances show like structure expressed, not merely bysimilarity of form, but by like cleavage, twinning, and habit.(6) The substances have similar crystal structure, and may formmixed crystals, but do not belong to the same crystal sub-class.(7) The substances possess similar structure with identical sym-metry, and form mixed crystals, but are not chemically analogous.(8) The substances show chemical analogy in addition to theother characters.Zcitsch.Zryst. Min., 1912, 51, 417266 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.(9) Lastly, they possess chemical analogy, form mixed crystals,have similar structure, and angular relations which are functionsof the atomic weights of the interchangeable elements.It is clear, then, that no small difficulties beset all attempts togive a precise definition of isomorphism. Some of these have alsobeen commented upon by T. V. Barker,% who has called attentionto a number of cases of what he terms unusual types of isomorphism,where close similarity of form is associated with great divergenceof chemical type. As examples may be quoted, the compoundsCuTiF,4H20, C’uCbOF,,4H20, and CuW02F,4H,0, which are allisomorphous and oblique, or KClO,, BaSO,, and KBF,, which areisomorphous and orthorhombic, or, again, the well-known case ofCaCO, and NaNO,, which are closely isomorphous and rhombo-hedra]. Barker points out that on the ordinary theory of valencyno strict chemical similarity can be demonstrated between themembers of the above groups, and the same holds good for manyothers which he enumerates.If, however, the co-ordination theoryof Werner be adopted, analogies at once become evident, as may beseen if the members of the first group of compounds quoted abovear0 written in the following form:[TiFJCu + 4H,O ; [Cb:ACu + 4H,O ; [ W$]Cu + 4H,O.I n developing his argument, Barker draws attention to the greatdifficulties which attend the application of the Pope-Barlow theoryto these complex inorganic compounds, and points out that theconception of a single valency volume may lead to conclusionswhich are mutually inconsistent. It is obvious that the views putforward in these two communications may be expected to lead tomuch further discussion and research.Artificial Formation of Minerals.The workers a t the geophysical laboratory in Washington havepublished in detail the results of an elaborate investigation into theconditions of formation and mutual relations of the mineralsulphides of iron.35 They find that crystals of marcasite can beobtained by the action of hydrogen sulphide on ferric salts or bythe action of hydrogen sulphide and sulphur on ferrous salts.Lowtemperatures and the presence of free acid favour its formation,pure marcasite being produced in a solution containing 1 per cent.of sulphuric acid.Less acid solutions and higher temperaturesgive mixtures of marcasite and pyrites. The latter mineral is34 T., 1912, 101, 2484.35 E. T. Allen, J. 1,. Crenshaw, J. Johnston, and E. S. Larsen, Amcr. J. Xci.,1912, [iv], 33, 169 ; A., ii, 354MIKERALOGlCAL CHEMISTRY. 267formed by addition of sulphur from solution to amorphous ferroussulphide or to pyrrhotite and by the action of soluble polysulphidesor thiosulphates on ferrous salts. When heated to 450° marcasiteis slowly converted into pyrite with evolution of heat, the changebeing an irreversible monotropic one.These observations are in accord with the f a c t that althoughpyrite may occur as a primary constituent of magmas, marcasite isnot so formed.Pyrite occurs in deep veins and in the neighbour-hood of hot springs, where it is deposited from water more or lessalkaline. Marcasite, on the other hand, occurs in surface veins,and was deposited from cold acid solution. On heating, pyrite isconverted into pyrrhotite, the change being a reversible one, andtaking place about 565O, for it was found that when heated at 550°in hydrogen stdphide pyrrhotite paased into pyrite, whilst thereverse change took place rapidly at 575O. Pyrrhotite is alsoproduced by heating iron with excess of sulphur, and there is strongreason to believe that the composition of pyrrhotite is not constant,the mineral being really a solid solution of sulphur in ferroussulphide. From observations of the specific volume of syntheticalpyrrhotite it is inferred that saturation occurs with 6.5 per cemtlof sulphur, a conclusion which agrees with the maximum percentageof sulphur observed in natural pyrrhotite.Examination of the synthetical crystals of pyrrhotite confirmsthe view that the substance is dimorphous.One form, a, stable athigh temperatures, is orthorhombic, with close approximation toangles of 60° in the prism zone. It is characterised by considerabledevelopment of the basal plane, and is usually elongated parallel tothe X axis. The form /3, stable at low temperatures, is hexagonal,and almost invariably forms cruciform twins. The dominant formsare the prism and a aharp pyramid.Troilite is not to be regardedas a distinct species, but is the end member of the pyrrhotite series;it has not so far been prepared free from iron.A most interesting study of the transformation and conditions offormation of the sulphides of zinc, cadmium, and mercury has alsobeen undertaken in the Geophysical Laboratory.36 It has beenfound that the change of sphalerite (zinc blende) to wurtzite is areversible one, and takes place about 1020O. The reverse changeoccurs slowly, and requires sixty-six hours to complete a t 800-9OOo.The density of wurtzite, 4.087, is slightly less than that of sphalerite,4-090, and the index of refraction of the latter, 2.3688, lies betweenthose of wurtzite, o =2*356 and e=2*378. Iron sulphide which sofrequently occurs in solid solution in natural sphalerite increases36 E.T. Allen, J. L. Crenshaw, and H. E. Merwin, A,mer. J. Sci., 1912, [iv], M,341 ; A,, ii, 1055268 ANNUAL REPORTS ON THE PROGRESS OF CHEMTSTRY.the specific volume, and also the refractive index, but greatlydiminishes the inversion point, the effects being proportional to theamount of iron present.Fair-sized crystals of wurtzite were obtained by sublimation a t1200-1300°, whilst small dodecahedra of sphalerite were got frommolten sodium chloride about 800°, and larger dodecahedra andtetrahedra from potassium polysulphide a t 350O. From aqueoussolutions both forms were deposited in crystals between 200° and400O. Hydrogen sulphide precipitates both forms from acid solu-tions at 250°, the production of sphalerite being favoured by raisingthe temperature, and that of wurtzite by increasing the acid con-centration. Cadmium sulphide exists in but one form, which canbe got in good crystals identical with those of greenockite by theaction of hydrogen sulphide on cadmium vapour.Mercurysulphide, on the other hand, exists in three forms. The first,cinnabar, D 8.176, is the most stable form, and is readily preparedby digesting either of the other forms with a solution of alkalisulphide. The second, meta-cinnabar, D 7-60, is black and cubic,and is precipitated from dilute acid solutions of mercury salts bysodium thiosulphate. The third is a new red form obtained aa afine, crystalline powder from stronger neutral solutions on additionof sodium thiosulphate.It is worthy of remark that we observe again here what hasalready been noticed in the case of pyrite, that the unstable formsof the sulphides are deposited from acid sohtions and the stableforms from alkaline solutions, although under certain conditions oftemperature and concentration they may also be obtained from acidsolutions.New Ninerals.AZbanite.-This name has been given to a black, lustroussubstance of a resinous aspect found in Albania.37A Zlcharite.-Three crystals of a mineral resembling antimonitein appearance were found with urbaite at Allchar in Macedonia.Accurate measurements obtained from one of these crystals showed,however, tha-t the angles of this substance were not only differentfrom those of antimonite, but could not be identified with those ofany known species.% The system is orthorhombic, a : b : c=0.9284 : 1 : 0*6080, and the forms present {OlO}, { l l O } , {210},A mpangabe'ite is a hydrated columbo-tantalate containinguranium found a t Ampangabe' in Madagascar, where it is met with37 C.I. Istrati and M. A. Rlihailescn, C?te?n. Zentr., 1912, i, 158T ; A., ii, 773.38 13. JeIek, ZeitsclL. Kryst. Mift., 1912, 51, 275.{Oll), (1011, (111)MINERALOGICAL CHEMISTRY. 269in large, brownish-red, elongated, rectangular crystals, which aresaid to resemble Br5gger’s %me1 odit,e.39Arduinite.-A zeolitic mineral from Val dei Zuccanti has beenanalysed by E. Billo~s,4~ who finds that the composition may beexpressed by the formula H,,CaA1,Na4Si,03,.As the properties ofthe substance differ somewhat from those of the known zeolites, hebelieves it to be a new species.Arsenoferrite.-The dark brown, pseudomorphous crystals similarin habit to iron-pyrites which occur on gneiss a t the Binnenthal,Switzerland, have been found on analysis to contain iron andarsenic in the ratio 1 : 2. It seems likely, therefore, that they origin-ally consisted of FeAs2, for which hypothetical mineral the namearsenoferrite is therefore proposed.4fBaeumZerite.-A colourless, transparent, and highly deliquescentmineral occurs in thin bands in the rock-salt of the Desdemona saltmine in the Leine valley.42 The substance possesses three perfectcleavages a t right angles to one another or approximately so. It isoptically biaxial and negative.The composition is KC1,CaC12, andaccording to Zambonini it is therefore probably identical withchlorocalcite, a mineral from Vesuvius described in 1872 by Scacchi,which has the same composition, and was described as crystallisedin cubes with cubic cleavage.43Betcljik-This mineral, a hydrated, uraniferous columbo-titanate, occurs at Ambolotara, Madagascar. It has already beendescribed as bl~mstrandite,~~ by A. Lacroix 45 now considers that itshould rank as a separate species.ChrombrugnateZZite.-A scaly, micaceous mineral occurs as lilac-coloured, lenticular masses in a bright green serpentine fromDundas, Tasmania,46 I t s composition appears to be :2MgC03,5Mg(OH)2,2Cr(OH)3,4H,0,which is somewhat analogous to that of brugnatellite,Cryptose.-From a discussion of the composition and propertiesof a felspar from San Bartholomeu, Alcobaga, V.Souza-ljlanciih 4739 A. Lacroix, Compt. rcnd., 1912, 154, 1040; A . , ii, 567. See also L’ull. SOC.franq. Nin., 1912, 35, 180.Extract from Rivista Min., 1912, 41.41 H. Baumhauer, Zeitsch. Kryst. Min., 1912, 51, 143 ; A., ii, 949.42 0. Renner, Centr. Min., 1912, 106 ; A., ii, 357.44 Ann. Bepurt, 1911, 255.45 Compt. rcnd., 1912, 154, 1040 ; A., ii, 567.46 L. Hezner, Centr. Min., 1912, 569; A., ii, 1061.47 C‘oirmun. Comm. Sew. Geol. Portugal, 1910-1911, 8, 12.F. Zambouini, ibid., 270 ; A., ii, 652.See also Bull. SOC. franc Nin.,1912, 35, 88270 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.concludes that albite can exist in polysymmetnc, oblique crystals,that is to say, in crystals having all the geometrical properties ofthe oblique system, but composad of microscopic lamelk twinnedaccording to the albite law.These lamellae may be so thin it9 t obe indistinct even under the highest powers of the pollarising micro-scope. For this variety which bears t o ordinary albite the relationof orthoclase to microcline, he proposes the name cryptose or krypto-klas.DidymoZite.-Greyish-white crystals somewhat resembling kyanibin appearance occur in crystalline limestone on the Tatarka river,Yeniseisk, Siberia.& They are oblique (a : b : c =0.6006 : 1 : 0.2867 ;p = 106”), and invariably twinned. Their composition is representedby the formula 2Ca0,3A1,03,9Si0,.Hat chit e.-Five minute crystals of a lead-grey mineral, probablya sulpharsenite of lead, were found in the Lengenbaeh quarry inthe Binnenthal in 1902. They cannot be identified with any of thenumerous minerals already described from that locality, and aretherefore regarded as belonging to a new species.49 They crystallisein the anorthic system with the following constants : a= 116O53$’,B = 85O121, y = 113°44Qf; a : b : c = 0.9787 : 1 : 1.1575.Manandorrite.-This interesting mineral has been met with incavities in the pegmatite veins of Antandrokomby, Madagascar,associated with rubellite and quartz. It occurs as white laminze, oras mamillary crusts of hexagonal plates.50 It possesses a micaceouscleavage with pearly lustre.A cleavage flake viewed in polarisedlight exhibits six regular sectors. An acute positive bisectrixemerges perpendicular to the plate, and the optic axial angle inair is about 30°. The composition may be represented by theformula Si,O5,B4A1,,Li4H2,. Water is not expelled until themineral is heated above 120O.iKeZnikowite.-A variety of iron sulphide has been described,which is said to have the same cornposition as pyrite, but is muchmore easily attacked by acids and other reagents. It is thereforeregarded as a labile form of iron disulphide, which differs frompyrite and marcasite, and the name melnikowite is proposed for it.61PaZuite.-Crystalline masses of a flesh-coloured mineral occur inthe tourmaline mines of Pala, San Diego Co., California.It hasresulted from the alteration of lithiophilite, and has the composi-tion 5Mn0,2P,O5,4H2O.62Ponite.-This name has been assigned to a greyish-pink carbonateA. Meister, Jahrb. Min., 1912, i, 403 ; A., ii, 950.49 R. H. Solly and G. F. H. Smith, Min. May., 1912, 16, 287.50 A. Lacroix, Bull. SOC. franq. Min., 1912, 35, 225.5l B. DOSS, Jahrb. Min. Bei2.-Bd., 1912, 33, 662.52 W. T. Schaller, J. Washi?tgto?z Acad. Sci., 1912, 2, 143; A., ii, 456MINERAIaOQICAL CHEMISTRY. 271of the formula FeC03,5MnC03, found in the Borca Valley,Roumania.MPreslite, see Tsumebite.Riva&.-This new Vesuvian mineral having the formula(Ca,NaJSi205, was recently described by F. Zambonini.54Salmonsite.-This name has been assigned to a manganese andiron phosphate found as buff-coloured masses a t Pala, California.55It appears to have been produced by the alteration of hureaulite,and has the formula Fe2O3,9Mn0,4P,0,,14H20.Samiresite occurs as fragile octahedra a t Samiresy, Madaga~car.5~It is related to blomstrandite and betafite, but differs from thelatter in containing more columbium and less titanium.It alsocontains a considerable quantity of lead (7.25 per cent. PbO) as wellas uranium.Sheridanite.-This mineral is a variety of chlorite approximatingto leuchtenbergite. It contains an unusually large percentage ofalumina, and a very small amount of iron, the composition beingrepresented with fair accuracy by the formula H,Mg3A12S~0,3. Itoccurs in some quantity as a foliated mass of pale silvery-grNnscales in Sheridan Co., Wyoming.57Sicklerite and 8tewartite.-These two minerals are alterationproducts of lithiophilite found at Pala, San Diego Co., California.68The former occurs as dark brown cleavage masses of high refractiveindex (1.74) and moderate birefringence, and has the formulaFe20,,6Mn0,4P20,,3 (Li,H),O.The latter, although it occurs inabundance, is so mixed with other minerals, that a pure samplecould not, be obtained for analysis. It is a hydrated manganesephosphate, and occurs as fine, pleochroic fibres of high birefringence,arranged normally to the cleavage cracks of the lithiophilite.Tsumebite or Pres1ite.-A crystalline, emerald-green mineraloccurs with azurite, zinc carbonate, and dolomite a t Tsumeb, Otavi,German South-West Africa.The density of the minute, obliquecrystals is 6-13. It is a hydrated phosphate of lead and copper ofthe composition given below, and was named tsumebite byI(. Busz:PbO. CUO. PZO5. H,O. Total.63.77 11-79 12-01 12-33 99.90These numbers lead to the formula 5(Pb,Cu)O,P,O5,8H20, theH&5( P0,),,433@,53 V. C. Butureanu, Ann. Sci. Univ. Jassy, 1912, 7, 183.O4 Rend. Accad. Sci. Fis. Mat. Napoli, 1912, [iii], 18, 223.‘55 W. T. Schaller, J. Washington Acad. Sci., 1912, 2, 143 ; A., ii, 456.O6 A. Lacroix, Compt. rend., 1912, 154, 1040; A,, ii, 567.67 J. E. Wolff, Arner. J. Sci., 1912, [iv], 34, 4’15; A., ii, 1181.58 W. T. Schaller, loc. cit272 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.ratio of lead to copper being approximately 2 : 1.The same mineralhas been described by V. ICoswky under the name preslite.59 Hisaccount agrees with that of BUSZ, except that he believes the crystalsystem to be orthorhombic instead of oblique.VoeZcke&e.-This name has been proposed for a hypotheticaloxy-apatite, 3Ca,(P04)2,Ca0, which is believed to be a constituentof many members of the apatite group.60Vrbaite.-This interesting mineral is a well-defined substanceoccurring in good crystals in a mixture of earthy realgar andorpiment a t the Allchar mine, Macedonia.61 It is orthorhombic(a : b : c = 0.5659 : 1 : 0.4836). The habit is either tabular parallelto 010, the cleavage plane; and these crystals show also faces of theforms {loo}, {331}, { l l l } , and {112}, or pyramidal with the form{ 111 } predominating.Small crystals are deep red and translucent,larger ones bluish-black and opaque. The streak is similar to thatof proustite. Tbe density is 5.3, and on analysis the substanceproved to be a thallous salt of the formula TlAs.@bS,, derived fromthe acid HA@,.I n addition to the above we must here take note of certainother substances which may possibly prove to be new species, butto which so far no names have been assigned. One of these hasbeen observed in minute, blue crystals on sandstone a t the mine,Etoile du Congo, Katanga, Congo Free State.g2 The mineral appearsto be a hydrated phosphate of copper and cobalt. It is ortho-rhombic, and the crystals are very similar, both in angles and inoptical properties to those of libethenite.Another substance not as yet fulIy determined occurs as smallnodules in the guano deposits of R6union.a It is soluble in water,and is a hydrated sulphate of ammonium and potassium, possiblythe potassium analogue of lecontite, (Na,NH4),S0,,2H2O.G.D’Achiardi 64 has recorded the existence of minute crystals of amineral containing copper and sulphur in the Carrara marble, butits exact nature remains obscure.Another mineral the characters of which do not seem to agreeexactly with those of any known species has been found in minute,green, oblique crystals on copper ore from Atacama.65 It is suggestedthat i t is a kind of natrochalcite having the formula:59 Zeitsch. Kryst. Min., 1912, 51, 521.Go A.F. Rogers, Amer. J. Sci., 1912, [iv], 33, 475; A., ii, 565.G1 B. Jeiek, Zeikch. Kryst. Min., 1912, 51, 365.63 A. Lacroix, Bull. SOC. f r a q . Min., 1912, 35, 114.65 P. Walther, Nature, 1912, 89, 322.G. Ceshro, Ann. SOC. Gkol. Belg., Publ. red. au Congo Belge, 1912, Fasc. 11, 41.I’roc. verb. SOC. Toscam Sci. Nat., 1912, 20, 54, 77.See Ann. Report, 1909, 224MINERALOGICAL CHEMISTRY. 273Mineral Analyses.A ZZophane.-Discussion still continues as to the nature of thesubstances grouped together under this name. The view held byStremme 66 that they consist of mechanical mixtures of colloidalhydrated alumina and silica being combated by S. J. Thugutt,67 whopoints out many differences between the natural minerals and arti-ficial products.He supports his contention by analyses of anauxiteand cimolite, which point to the individuality of these species.AZumgen.-As the result of an investigation of an occurrence ofalunogen and halotrichite from New Zealand, J. Uhlig68 has cometo the conclusion that the formula of the former mineral isAl,(S0,),,16H20, whilst it is still an open question whether thelatter is FeA12S,0,,,24H,0 or FeA1,S40,,,22H20. He points outthe special value of refractive index determinations for the identi-fication of these substances.Amphibole Group.-A number of members of this group havebeen nnalysed, and we may call attention to an emerald-greenactinolite from Sardinia,69 to two hornblendes from CentralFrance,70 which contain but little titanium, and to an amphibolefrom Hungary 71 exceptionally rich in this element.d patit e GToup.-The analysis of a calcium carbonato-phosphatecalled dahllite (= podolite) occurring in minute, hexagonal crystalsa t Tonopah, Nevada, has given occasion for a critical discussion ofthe published analyses of the apatite group.7, As a result of this,Rogers concludes that the members of the group are to be regardedas isomorphous mixtures of fluor-apatite, 3Ca3(P0,),,CaF2, chlor-apatite, 3Ca3(P04),,CaCl,, and carb-apatite, 3Ca3(P0,),,CaC03,together with a substance not hitherto recognised as entering intothe composition of the group, namely, oxy-apatite, 3Ca3(P04),,C'a0,for which the name voelckerite is proposed.H e also points outthat carbon dioxide has been recognised for some time as anessential constituent of apatite, and that 3Ca3(P0,),,CaC0,actually exists, not only as dahllite, but also as the main constituentof certain ill-defined rock phosphates. He has, moreover, made theAnn.Rcport, 1911, 253.G7 Centr. Jii?i., 1912, 35 ; A., ii, 267. See also Th. A. Nikolaevski, Bull. Acad.Imp. Sdi. J't. Pdtcrsbowg, 1912, [vi], 6, 715, who proposes the name shangavskitefor a hydrated colloidal alumina containing about 41 per ceut. of water.G8 Ibid., 723, 766.69 D. Lovisato, Atti 1:. Accad. Lincei, 1912, [v], 21, i, 105 ; A., ii, 358.70 P. Gonnard and P. Barbier, Bull. SOC. f r c q : . AfiiL., 1911, 34, 228 ; A., ii, 360.71 13. hlauritz, PijZd. Koxlony, 1910, 40, 551.t2 A. F. Rogers, Amer. J.Sci., 1912, Liv], 33, 475 ; A., ii, 565.KEl'.-VOL. 1s. 274 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.interesting observation that some varieties of pyromorphite alsogive indications of the presence of carbon dioxide.Somewhat similar conclusions have been reached by W. Tschir-winsky,73 who, in the course of his study of Russian phosphorites,distinguishes the following five groups : (1) fluor-apatites, (2)podolites, (3) those with the composition 2Ca3(P0,),,CaC03,CaF2,(4) those with the composition 3Ca3(P0J2,2CaC03, (5) phosphoritesin which the cementing material consists largely of aluminium andiron phosphates.74It is interesting to note that fluor- and chlor-apatites have beensynthesised by fusing calcium phosphate with fluorite or calciumchloride respectively, and it has also been shown that the twoapatites form a continuous series of mixed crystals.75A waruite.-Steel-grey, irregular grains of this mineral from thegold-washings on the Pelly River, Yukon, contain 74.34 per cent.of nickel and 21-35 per cent.of iron.76Aximite.-An analysis of hair-brown crystals from Nickel PlateMountain, British Columbia, has been published by R. A. A.Johnston.77Bddeleyite.-The occurrence of minute crystals and grains ofthis very rare and interesting mineral, native zirconia, is reportedfrom near Bozeman, Montana, where it is found in a corundum-s yenit e.78Bastnaesite.-This rare mineral has been met with in Madagascarin cleavage masses somewhat like the zinc-blende from Santanderin appearance.79 The mineral is optically uniaxial, and the smallerof the two indices has been found to be 1.7145 (Na).It is solublein sulphuric acid with evolution of carbon dioxide and hydrofluoricacid, and on examination with the spectroscope absorption bandsdue to didymium were seen. A quantitative analysis proved it to bea fluocarbonate of cerium, lanthanum, and didymium similar incomposition to the bastnaesite from Cheyenne Mountain, nearPike’s Peak. The same mineral has also been met with a t Welge-vonden, S. Africa, in hexagonal prisms.80Bauxite.-The composition of a number of bauxites especiallyfrom Croatia has been determined by M. KiGpatiE, who has likewisediscussed the mode of origin of the substance and the accessory73 Jahrb.Min., 1911, ii, 51 ; A., ii, 173.74 For analyses of a number of other Russian phosphorites, see A., ii, 949.75 R. Nacken, Ccntr. Bin., 1912, 545 ; A., ii, 1061.76 R. A. A. Johnston, Summary Rep. Geol, Surv. Canada, 1911, 256 ; A., ii, 358.i7 Ibid.7* A. F. Rogers, Amer. J. Sci., 1912, [iv], 33, 54 ; A, ii, 172.79 A. Lacroix, Bull. Soc. franc. hfin., 1912, 35, 108.D. P. McDonald, Trans. Geol. SOC. S. Africa, 1912, 15, 74MISERALOGICAL CHEMISTRY, 275minerals it contains.81 From his observations he has come to theconclusion that bauxite is a residue derived from dissolved lime-stones and dolomites, and consists for the most part of a colloidalhydrated aluminium oxide, Al,O,,H,O, which he terms sporogelite,together with diaspore, hydrargillite, and certain characteristicaccessory minerals.As it is a mixture of variable composition onecannot speak of pure or impure bauxite. E. Dittler andC. Doelter 82 have also occupied themselves with the composition,classification, and nomenclature of bauxite and allied substances.They have declared themselves adherents of the view that bauxiteconsists of a colloidal aluminium hydrate, and by treating thesesubstances with dyestuffs they distinguish between true bauxiteand a mixture of the gel with diaspore, hydrargillite, limonite, andkaolin, thus adopting the position of Cornu, who gave the namekliachite to the isotropic bauxite substance.Beryl.-From their examination of the beryls of Madagascar,Duparc and his assistants came t o the conclusion that two typesof this mineral exist.One is of prismatic habit, exhibits few.forms,has a relatively low density and indices of refraction, and containsbut little alkalis; the other is tabular in habit with a large basalplane; it possesses a higher density and refraction indices than theother type, and contains a considerable quantity of rubidium andczsium. These conclusions were criticised by Lacroix, who believesthat the beryls form a continuous series.83 I n a recent paper,Duparc84 maintains his original position, and quotes in support ofhis view two new analyses: (I) of a blue aquamarine from Ambato-lampy, and (11) of a green aquamarine from Sahanivotry, both ofwhich belong to his first type. The composition and properties ofthese beryls are very similar to those of the pink beryl fromTsilaisena, but differ considerably from those of the tabular berylof Maharitra, which is typical of the second type, and may reason-ably be classed as a separate variety under the name vorobyeviteproposed by Vernadsky.I n reply, Lacroix86 has reviewed all theascertained facts as to the properties, especially the density, ofberyls from Madagascar, and expresses his conviction that it isimpossible to admit the existence of two distinct types of beryl.It is interesting to notice that his views are confirmed by the resultof a recent careful study of the composition and properties of threeberyls from Elba.8681 Jahrb. Min. Bei1.-Bd., 1912, W, 513.82 E. Dittler and C. Doelter, Centr. Min., 1912, 19, 104.83 Ann.Report, 1911, 254.84 L. Duparc, 11. Wunder, and R. Sabot, Bull. SOC. f r a q . Nin., 1912, W, 239 ;86 L. Maddalena, Atli R. Accad. Lincei, 1912, [v], 21, i, 633 ; A., ii, 775.A., ii, 360. 8s A. Lacroix, ibid., 1912, 35, 200.T 276 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Bismuth.-An interesting occurrence of bismuth is reported fromthe pegmatite vein of Madagascar, where the element has been foundnative and SLS sulphide, both converted for the most part into abasic carbonate.87Clintonite Group.-A specimen of brandish from Tiriolo (Catan-zaro) was found to be unusually rich in magnesia.aCarnotite.-An anaIysis of a small quantity of this mineral foundas a light yellow powder at Mount Pisgah, Pennsylvania, supportsthe view that the species is a definite one belonging to the uranitegroup.The formula is (Ca,K2)(U02)2(V04)2,zH20, a result inharmony with those of analyses of material from Colorado andSouth Australia.89Ce2estite.-A specimen containing 3.2 per cent. of bariumsulphate, but no calcium, has been found in limestone near Inns-br~ck.~ODolomite.-Minute, rhombohedra from the limestone of theWetterstein, near Innsbruck, were found on analysis to have asomewhat abnormal composition, the results agreeing roughly withthe formula 7CaC03,4MgC03.91 A specimen of brown spar from thesame district may be represented as 4CaC03,4MgC03,FeCY),.A white mineral observed as thin seams along the joint-planes ofcoal proved on analysis to be ankerite.93 One specimen had nearlythe normal composition, 2CaC03,Fe(Mn)C03,MgC03. An analysishas also been published of a ferriferous dolomite from the SimplonTunnel .93Ep'dote.-Good crystals of epidote occur in pegmatite veinstraversing granulite a t Notodden, Telemark.94 These have been thesubject of a thorough crystallographic and optical study, and bothgreen and red crystals have been analysed.The results lend supportto the idea that the red colour of many epidotes is due to thepresence of tervalent manganese. A consideration of the seriesiron epidobclinozoisite leads to the conclusion that a change inthe amount of ferric iron of 0.3 per cent. alters the birefringencet o the extent of 0.001.Pelspur Group.-I?. Gonnard and P. Barbier 95 have continuedtheir work on French felspars, and have published two analyses ofmicrocline and two of orthoclase, whilst to N.Orloff is due ana7 A. Lacroix, B16zl. SOC. franq. Jfin., 1912, 35, 92.88 U. Panichi, Atli R. Accad. Lincei, 1911, [v], 20, ii, 518 ; A., ii, 57.89 E. T. Wherry, Amtr. J. Sci., 1912, [iv], 33, 574 ; A . , ii, 774.A. Haas, Jnhrb. Vin., 1912, i, 1 ; A . , ii, 564.91 Ibid.92 T. Crook, Min. Mug., 1912, 16, 219 ; A., ii, 565.y3 M. Delgrosso, Riv. Hin., 1912, 41, 56.S4 0. Andersen, Archiv Math. og ATnlz~rv., 1911, 31, No. 15 ; A . , ii, 1183.95 Bull. SOC. Min., 1911, 34, 235 ; A., ii, 359MINERALOGICAL CHEMISTRY. 277investigation of a number of anorthoclases from Pyatigorsk,Caucasia 96; the latter all contain barium, but no strontium.Speci-mens of labradorite sufficiently pure to repay detailed chemical andphysical examination have been described in recent years by Fordand Bradley and by Bonillas 97 respectively. Material very similarto the above has been found in basalt dykes in Co. Down, 1rela11d.O~The density of the perfectly fresh transparent crystal fragments is2.706. The indices of refraction are a=1*5630, P=1*5665, andy=1*5712, and t h e extinctions are - 1 1 O on c(OO1) and -23O onb(010). The composition of the mineral is closely represented bythe formula 33NaA1Si30,,5KA1Si,0,,62CaA12Si208.FichteZite.-A crystallographic investigation of this curioushydrocarbon, C18H23, has shown that the natural crystals fromKolbermoor, neax Aibling, have no plane of symmetry, but belongto the hemimorphic class of the oblique system.ggGarnet Group-In the course of an important investigation ofthe chemical composition of the crystalline schists, cordierite rocks,and sanidinites of the Laacher See region, R.Braunsf quotes anumber of analyses by J. Uhlig of the included garneb.Hniiyne.-Good crystals of the variety of this mineral termedberzeline, pure enough to repay careful analysis, have been found inpeperino near Ariccia.2 Their composition agrees very closely withthat calculated from the formula proposed by Brogger and Biick-strom, (Si04)3Al,(A1*S0,Na)Na4, which may be written in a formanalogous t o that of the garnet formula.ZhZeite.-An orange-yellow hydrated iron sulphate found as anefflorescence on graphite a t Mugrau, Bohemia, witg described bySchrauf in 1877 under the name ihleite.A very similar substancehas recently been observed with iron ores a t two localities in theisland of Elba.3 On examination under the microscope the mineralwas seen to consist of minute, rhombic or hexagonal plates possess-ing optical characters in accord with orthorhombic symmetry. Onanalysis the material from both localities was found, after deduct-ing impurities, to agree with the formula 2Fe20,,5S0,,16H2O. Acomparison of the properties of the substance with those of twospecimens of copiapite, one from Tierra Amarilla and the otherfrom Copiapo, leads to the conclusion that ihleite is identical withcopiapite, and that the latter mineral is to be regarded aa ortho.96 Annuaire Gkool.Min. Eussie, 1911, 13, 21 ; A., ii, 950.97 Ann. Report, 1911, 257.98 A. Hutchinson and W. C. Smith, Min. A l f a g . , 1912, 16, 267.99 A. Rosati, Zeitsch. Kryst. Min,., 1912, 50, 126.1 Jahrb. Milt. Bed.-Bd., 1912, %, 85.a N. Parravano, Atti R. Accad. Lincei, 1912, [v], 21, ii, 631.3 E. Manasse, Proc. verb. SOC. To~cann Sci. Nut., 1911, 20, 65278 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.rhombic, and not as oblique as is generally stated.4 Analysm ofthe specimens from Tierra Amarilla and from Copiapo confirm theformula given above.IZmenite.-The view that ilmenite is tm be regarded as FeO,TiO,,rather than as Fe203,Ti203, receives support from analyses of atitaniferous ore from Ekersund, and of an ilmenite crystal fromthe Urals.6 Titanium was precipitated by boiling a solution of thepotassium hydrogen sulphate melt, iron being first reduced bysulphur dioxide.Total iron was estimated in a solution reducedby sulphur dioxide and ferric iron iodometrically in a hydrochloricacid solution made in absence of air. Confirmatory evidence infavour of this view is found in the fact that whereas compoundscontaining tervalent titanium evolve hydrogen when treated withalkalis, ilmenite does not. Its behaviour, moreover, towardssulphuric acid is similar to that of a mixture of titanic acid and afarrous salt.1ridosmine.-Very small quantities of this mineral have beenfound in battery concentrates a t the New Rietfontein Mines, SouthAfrica.6 A sample analysed was found to consist of 95.5 per cent.of iridosmina containing about 45 per cent.of iridium. In thisconnexion attention may be called to a useful summary of all theelements found native compiled by W. Vernadsky.7Rornerqzne.-Some crystal fragments, seagreen in colour, andsufficiently transparent to be cut as gem-stones, have recently beendescribed by A. Lacroix from the pegmatites of Madagascar.* Thedensity is 3.27, and the refractive indices as follows: a=1*6613,p= 1.6733, y = 1.6742. The composition is represented by theformula 6 (Mg,Na,,&,H,) 0,4 (AI,Fe),03,5 SiO,, which differs some-what from the formula, MgO,A1,O3,SiOz, usually accepted for themineral.Lorandite.-A single crystal of this rare thallium compound,TlAsS,, has been identified on a matrix of iron-pyrites and barytesfrom the Rambler mine, near Encampment, southern Wyoming.9Libneburgite.-The results of a new analysis of this mineral maybe expressed by the formula Mg3(P04),1*77H3B03,6H20.10 Thedehydration curve shows that 6H20 are lost sharply at ZOOo, theremainder passing away slowly up to 600O.Marcasite Group-The important work on the mineral sulphidesAnn.Xeport, 1907, 298.W. Manchot aud B. Heffner, Zeitsch. anorg. Chem., 1912, 74, 79 ; A., ii, 265.C. B. Horwood, Trcms. Geol. Xoc. S. Africa, 1912, 15, 51.Centr. Mi%., 1912, 758.8 Cmpt. rmd., 1912, 155, 672 ; A . , ii, 1182.9 A. F. Rogers, Amer. J. Sci., 1912, [iv], 33, 105 ; A., ii, 265.lo W, Biltz and E. Marcus, Zeitsch. anorg. Chem., 1912, 77, 124 ; A., ii, 1181MINERALOGICAL CHEMISTRY. 279of iron carried out at the Geophysical Laboratory in Washingtonhas been already referred to, and attention must here be called toa lengthy discussion on the part of A.Beutell11 of the relationshipsof marcasite, mispickel, and glaucodote. He comes to the conclusionthat the composition of mispickel is FeS,+nFeAs,; the normalmineral is not, however, to be regarded as an isomorphous mixtureof FeS, and FeAsz, but as an individual compound, variations ofcomposition being due to admixture of marcasite on the one handor of labile Fe,As, on the other. Marcasites which contain arsenicare to be regarded as mixtures of marcasite and mispickel. Theformula of mispickel is a t least Fe,S,As,, and its constitutionJ?,<S'AI">Fe.The glaucodotes are not isomorphous mixtures of s- A sFeAsS and CoAsS, but mixtures of normal glaucodote, FeCoS,As,,of constitution similar to that of mispickel, with marcasite, Fe2As,,and usually mispickel also. The cobaltites are mixtures of Co,S,As2with FezS2As2, and usually pyrites, FezS4, normal cobaltite being/ C d ,represented as Aqm/hs.Nica Group.-The composition of a sericite which occurs ingreen talc-like aggregates in cracks in quartz strings near Tan-y-bwlch, North Wales, approximates very closely to that of amuscovite from Bengal, and conforms to type I of Clarke's formulae,Al( SiO,*R,) (SiO,=A1),.12MoEy bdenite.-Analyses have been published of specimens foundin quartz in the Stilo district of Calabria.13NepheZite.-The difficulties which stand in the way of a satisfac-tory representation of the composition of nephelite were referredto last year,l4 and it was then pointed out that the analyses alwaysshow an excess of silica above that required for the formulaNablSiO,.The view that this excess is present as silica held insolid solution has received confirmation from recent synthetical~0rk,15 which has demonstrated that when silica, alumina, andsodium carbonate are fused together in the proportions required t oform NaAlSiO,, some of the sodium volatilises, but whereas theexcess of alumina separates as corundum, no free silica can bedetected by the microscope. The mineral can, however, be repre-sented it9 consisting of mixtures of the three molecules, NaAlSiO,(soda-nephelite), KAISiO, (kaliophilite), and NaA1Si30, (albite).l1 Centr.Min., 1912, 225, 271, 299 ; A . , ii, 652.l2 A. Hiitchinson and W. C. Smith, Min. Mag., 1912, 16, 264.l3 R. Nasioi and E. BJschieri, Atti R. Accad. Lincei, 1912, [v], 21, i, 692l4 Ann. Report, 1911, 260.l5 N. L. Bowen, A7ner. J. h'ci., 1912, [iv], 33, 49 ; A . , ii, 176.A., ii, 773280 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Analyses 16 of nephelite occurring in intimate association with albitetend to show that the maximum value of the silica ratio is 2.2.Penninite.-Colourless, transparent, roughly hexagonal platesoccur associated with the ophicalcite at Recess, Connemara, Ireland,and have approximately the same composition17 as the compactvariety of penninite known as pseudophite, of which numerousanalyses from different localities have from time to time beenpublished.Pickeringit e.-A reexamination of a substance, called picro-allumogene, by Roster in 1876, and to which the formula2MgS0,,A12( S04)3,28H20was assigned, has established its identity with pickeringite,MgS04,A12( S0,),,22H20.18The latter formula has been confirmed by analyses of specimensfrom an iron mine in Elba, from crevices in slate near Lehesten,Saxe-Meinigen, and from the alum-shales of Wetzelstein, near Saal-f eld.l9PZagionite.-An elaborate crystallographic examination of speci-mens from Oruro, Bolivia, has been made by F.Zambonini. Thecomposition of these crystals agrees closely with that required bythe accepted formula 5PbS,4Sb2S3.20 The results of this investiga-tion have led Zambonini to discuss the relations existing betweenplagionite, heteromorphite, and semseyite.He traverses the viewput forward by Spencer that these minerals form a morphotropicseries, and believes rather that they constitute an isomorphous seriesof mixed crystals, of which the end members are 5PbS,4Sb,S3 and5PbS,2Sb2S,. He finds support for his conclusions in the syntheti-cal work of Jaeger and van Klooster,21 who, by the thermal analysisof the binary system PbS-Sb2S3, have demonstrated the existenceof two compounds, 5PbS,4Sb,S3 (plagionite) and 2PbS,Sb2S,(jamesonite), but have obtained no evidence of the formation ofcompounds corresponding with zinckenite, warrenite, hetero-morphite, semseyite, boulangerite, meneghinite, or geocronite.PyrophyZZite.-A. Haas22 has analysed an earthy, dull green t obrown mineral found in small quantities in ‘‘ Muschelkalk,” nearInnsbruck.I n composition it is intermediate between pyrophylliteand giimbelite.H. W. Foote and W. BI. Eradley, Amer. J‘. Sci., 1912, [iv], 33, 439; A., ii,569.I7 A. Hutchinson and W. C. Smith, Min. Mag., 1912, 16, 264.l9 H. Hess von Wichdorff, Centr. Uin., 1912, 42 ; A., ii, 266.2o Bivista Min., 1912, 41, 1.21 F. ill. Jaeger and ti. S. van Klooster, Zeitsch. nnorg. Chem., 1912, 78, 245 ;G. D’Achiartii, Proc. verb. SOC. Toscnna. Sci. Nut., 1310, 19, 25 ; A., ii, 174.A., ii, 1169. Jnhrb. Min., 1912, i, 12 ; A., ii, 564MINERALOGICAL CHEMISTRY. 281Pyroxene Group-In the course of a description of the rocksof the Los Archipelago, West Africa, A.Lacroixs has noticed agabbro which contains a monoclinic pyroxene. This mineral con-tains much magnesium, is almost uniaxial, and belongs to thegroup of substances described as enstatite-augites by Walil, and towhich Winchell assigned the name of pigeonite. Analyses havealso been published of interesting augites from the province ofR0me;4 and from the plateau of Central France25; the latter con-tains a considerable amount of titanium, and may be called titan-augites .Revdimkite.-An apple-green ferrimagnesian silicate containing6.2 per cent. of NiO, found in small quantities in a deposit ofchrome-ironstone in the Caucasus, has been referred to this species.2GRutiZe.-The composition and mutual relations of the mineralsof the rutile group have been discussed by W.T. Schaller.27 Heincludes in this group rutile, cassiterite, mossite, tapiolite, nigrine,iserite, ainalite, ilmenorutile, and striiverite, and from an exam-ination of the published analyses he concludes that all thesesubstances are to be regarded as isomorphous mixtures of two ormore of the following compounds : ferrous columbate, Fe(CbO,),,ferrous tantalate (tapiolite), Fe(TaO,),, ferrous titanate, Fe(TiO,),titanyl titanate (rutile), (TiO)(TiO,), stanyl stannate (cassiterite),(SnO)(SnO,), and ferrous stannate, Fe(SnO,),. Small amounts ofzinc arsenate, zinc stannate, ferrous arsenate, and manganous tan-talate may also be present.Of the minerals mentioned above as composing the group, onlytapiolite, rutile, and cassiterite are to be regarded as distinctspecies.Mossite is columbium tapiolite. Nigrine and iserite areiron rutile, ainalite is tantalum cassiterite, while striiverite fromPiedmont is to be considered a mixture of 29.9 per cent. of ferrouscolumbate, 27.4 per cent. of ferrous tantalate, 2.6 per cent. offerrous titanate, and 40.1 per cent. of titanyl titanate.It has recently been suggested that rutile may owe its colour tovanadium rather than to iron oxide, and the wide distribution ofvaoadiuni and chromium in small quantities has been confirmedby the analysis of various rutiles in which V,O, and Cr,O, have beenfound in quantities ranging up to 0.55 per cent. and 0.39 per cent.respectively.28Salt.-The older salt beds exploited in the Berlepsch mine a t23 Bull.SOC. franc. Min., 1912, 35, 26.24 N. Pnrravano, Atti X. Accad. Lincei, 1912, 21, ii, 469 ; A., ii, 1182.25 F. Gonnsrd and P. Barbier, Bull. SOC. fmne. Min., 1911, %, 228.% N. Besborodko, Jnhrb. Min. Bed. -Bd.: 1912, 341, 783.28 T. L. Watson, J. Washington Acad. Sci., 1912, 2, 431 ; A., ii, 1179.3 2 6 1 1 . U.S. Geol. Survey, 1912, No. 509, 9 ; A., ii, 773282 ANNUAL REPORTS ON THE PROGRESS OF CHENISTRY.Stassfurt have been the object of an elaborate and interestingchemicemineralogical in~estigation.~g Representative samples weretaken a t various depths in the deposit, and their constituentminerals were isolated and identified, and their relative proportionsdetermined.They include anhydrite, carnallite, kieserite, langbein-ite, loewite, salt, sylvite, polyhalite, and vanthoffite. The composi-tion of a specimen of the latter mineral agrees with the formula3Na2S04,MgS04. A discussion of the conditions of formation ofthis deposit in the light of van’t Hoff’s work leads to the conclusionthat the temperature could not have been less than 7 2 O when thesebeds were laid down.The crystallisation of salt from pure aqueous solutions, fromsolutions containing carbamide, and from an artificial ‘‘ sea-water ”have been carefully studied by C. Fastert.30 The principal resultsof this interesting piece of work are i ~ 9 follows: I n pure aqueoussolution the faces of a distorted cube grow equally fast.Additionof carbamide increases the solubility of the salt, and, as is wellknown, gives rise to the combination of cube and octahedron. Therelative development of these faces and their velocity of growthdepend on the amount of carbamide present. On evaporating anartificial sea-water a t 25O, salt crystallises in octahedra within thelimits of the upper carnallite region and the bischofite region ofvan’t Hoff. At 83” it crystallises in cubes, except within thebischofite region, where octahedra are obtained. Under these con-ditions the presence of magnesium chloride is the determining factorfor the production of the octahedral form.Sapphirine.-This mineral is present in small, greenish-blackgrains associated with rutile in a considerable dykelike mass con-sisting largely of ilmenite occurring in anorthosite rocks a t St.Urbain, Quebec.31 Their composition is given under I below.Trans-lucent crystal fragments of the same mineral have also beenreported from the pegmatites of Madagascar.32 They are deep bluein colour, and present a general resemblance to the Greenland speci-mens, although their density,. 3.31, and refractive indices,a=1*7042, 6=1*7074, y=1*7097, are somewhat less than those ofthe Greenland mineral. The results of an analysis are given under11. A comparison of the molecular ratios given under Ia and 110will show that in neither case do the results agree well with thecommonly accepted formula, 5Mg0,6A1,Os,2 SiO, :29 0. Riedel, Zeitsch.Kryst. Mila., 1912, 50, 139 ; A . , ii, 265.30 Jahrb. Min. BeX-Bd., 1912, 33, 265.31 C. H. Warren, Amer. J. Sci., 1912, [iv], 33, 263 ; A . , ii, 360.A. Lacroix, Compt. rend., 1912, 155, 762MINERALOGICAL CHEMISTRY. 283I. 11. Ia. IIa.SiO, ........... 13 *44 1 4 *90 2 '00 2 .ooA1,0, ............ 62 '98 62.55 5.54 4 *96 ............ 4.46 21 *201.78 } 4'54MgO 15 '28FeO ............ 9.08Spodumem.-Ths behaviour of spodumene on heating, and itsrelation to the products obtained by fusing together silicates oflithium and of aluminium have been the subject of several investi-gations.33 As regards its melting point, i t has been pointed outthat the true melting point is the temperature a t which the sub-stance passes from the anisotropic to the isotropic-amorphous condi-tion.It has been found that in this mineral double refractiondisappears in the case of fin0 powder after heating to 950O. Thedensity which is unaltered by heating to 920° is reduced from3.147 to 2.370 at 980°, whilst the heating curve shows a markeddiscontinuity at 950O. All these facts point to the melting pointbeing 950°, a temperature which marks, therefore, the upper limitof formation of the oblique crystals of spodumene. On heating to atemperature of 1O1Oo there seems reason to believe that a furtherchange occurs.34 In connexion with this work we may note thatthe thermal study35 of the binary system composed of the meta-silicates of lithium and aluminium has established the existenceof two compounds, 2Li,Si03,A12(Si0,), and Li,Si0,,A1,(Si0,)3.Thelatter appears to be very different from spodumene, which givesrise, however, to the same product when fused and cooled slowly.Striivem'te.-Black, lustrous grains from a tin-bearing alluviumon the Sebantun River, Kuala Kangsar district, Perak, have thefollowing composition 36 :TiO,. Ta,O,. Cb,O,. FeO. MnO. SnO,. SiO,. H,O. Total.45'74 35-96 6'90 8.27 trace 2.67 0-20 0.50 100*2.1These results support the view that struverite is an isomorphousmixture of tapiolite, Fe(Ta,Cb),06, in rutile, TiO,. A mineralwhich is probably a member of this group has lately been found inMadagascar in large, tetragonal crystals.37SuZphates.-Hydrated sulphates of aluminium, iron, and mag-nesium have been observed in veins in the Sonnenburg Tunnel ofthe Brenner Railway.% The material appears t o consist for themost part of halotrichite and altered epsomite, accompanied bymirabilite, picromerite, and glaserite.33 K.Endell and R. Rieke, Zeitsch. anorg. Chem., 1912, 74, 33 ; A . , ii, 266.a4 A. Brun, ibid., 75, 68 ; A., ii, 569.35 R. Ball6 and E. Dittler, ibid., 76, 39 ; A., ii, 758.96 T. Crook and S. J. Johnstone, Min. Mag., 1912, 16, 224 ; A., ii, 566,sI A. Lacroix, Compt. rend., 1912, 154, 1040 ; A., ii, 568.P8 A. Brunuer, Rivista Min., 1911, 40, 47284 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.Synchysite.-The identity of synchysite with the fluo-carbonateof cerium metals, parisite, suggested by Palache and Warren,sQ hasbeen confirmed by the study of the optical properties of the twominerals.As, moreover, the density is the same, and partialanalyses gave R,O,=60*95 and 60.71 per cent., CaO=11*96 and10.70 per cent. for synchysite and parisite respectively, theiridentity may be regarded as securely established.40Thorianite.-Three specimens of this mineral have recently beenanalysed. The first from Ceylon41 contains more uranium oxide(23'5 per cent. U,O,) and less thoria (65.4 per cent.) than mostof the thorianite previously examined. This may be explained byassuming that the mineral is an isomorphous mixture of uraniumand thorium oxides. The results obtained with the second lead theanalyst, M. Kobayashi,42 to the conclusion that two distinct typesof thorianite exist, the ratio Tho, : UO, being almost exactly 6 : 1in the one case and 2 : 1 in the other, the corresponding percentagesbeing Tho,= 78 and 60, U,O,= 15 and 33.The existence of thesesimple ratios does not support the view that thorianite is to beregarded as an isomorphous mixture of the two oxides. Thereappears, moreover, to be a certain amount of difference between thecrystals of the two varieties, those with blunt edges containing morethorium than those with sharp edges. The third specimen contains74-2 per cent. of Tho, and 14.1 per cent. of U02?TozcrmaZine.-A very important contribution to our knowledge ofthis mineral has been made by W. T. Schaller,44 who has attemptedto throw light on some of the difficulties-it presents by determiningthe physical characters (density, axial ratio, and refractive indices),as well its the chemical composition of carefully selected materialfrom the following localities, mostly in California : (1) pink crystalsfrom Elba, (2) red crystals from Mesa Grande, (3) pale greencrystals from Mesa Grande, (4) green crystals from Haddam Neck,Connecticut, (5) blue crystals from Pala, (6) black crystals fromRamona, (7) black crystals from Lost Valley.The most important of his conclusions are: (1) that Penfield andFoote's general formula, E120B2Si,0,,, holds good; (2) there is noreason to suppose that foreign material is held in solid solution inthe tourmaline; (3) the amount of alumina varies inversely as theamount of bivalent oxides present; (4) a large number of com-394041172.434344Ann. Report, 1911, 261.E.Quercigh, Atti B. Accnd. Lincei, 1912, [v], 21, i, 581 ; A., ii, 773.W. Jak6h ant1 S. Tottoczko, Bulb. Acad. Sei. Cracow, 1911, A, 558; A., ii,Sci. Rep TShokis Imp. Unit,., 1912, i, 201 ; A . , ii, 1181.S. D. Kusnetzoff, Bull. Acnd. Sci. St. Petersboztrg, 1912, [vi], 361 ; A . , ii, 456.Zeitsch. Kryst. En., 1912, 51, 321MINERALOGICAL CHEMISTRY. 285ponents, not less than eight, have to be assumed if the mineral isto be represented as an isomorphous mixture; (5) the physical pro-perties vary with the composition, but the data at present availableare too meagre to allow of the deduction of exact relationships.Tridymite.-It has recently been found 45 that tridymite canreadily be prepared in the form of minute, hexagonal plates byfusing sodium silicate with three times its weight of sodium phos-phate for six hours a t 1000°.Another variety of silica, cristo-balite, can be obtained by heating silica-glass in a porcelain furnace.When in a fine state of division the different varieties of silica differlittle in their behaviour towards sodium carbonate solution, butvary greatly in their solubility in hydrofluoric acid; thus, whenheated for an hour with 1 per cent. hydrofluoric acid, the percent-ages dissolved are as follows: quartz, 5.2; tridymite, 20.3; cristo-balite, 25.8; amorphous silica, 52.9.Tscheff kinite.-A black mineral somewhat resembling euxenite inappearance, but easily fusible before the blowpipe and readilydecomposed by acids with gelatinisation, is found in the pegmatitesof Madaga~car.~o Two analyses indicate that the mineral isanhydrous and contains large quantities of cerium, lanthanum,didymium, and titanium.l'urpuoise.-A very interesting occurrence of crystallised tur-quoise is reported from near Lynch Station, Campbell Co., Virginia,where it is found in minute, anorthic, bright blue crystals, whichpossess nearly the same habit and angles as crystals of chalco-siderite.47 An analysis of pure material gave results in harmonywith the formula, 6A1(OH),,Cu(OH),H,,(P04),, assigned to themiaeral by Penfield.Zeolite Group-The commonly accepted formula for analcite isNa,Al,(Si0,)4,2H,0, which requires that soda, alumina, silica, andwater should bs present in the ratio 1 : 1 : 4: 2.The ratios actuallyobserved agree with this formula so far as soda and alumina areconcerned; the silica and water ratios are, however, in most casesconsiderably too high, although the proportion 2 : 1 is approximatelymaintained. An attempt to clear up this discrepancy by analysesof carefully selected homogeneous material from various localities,has merely confirmed the results of early observations, the meanvalue of the ratios for six different specimens, each of which wasanalysed in duplicate, being as follows 48 :N+O : A1,0, : SiO, : H,O = 1 : 1.06 : 4-36 : 2.20.It is probably related to tscheffkinite.45 R. Schwarz, Zeitsch. anorg. Chcm., 1912, 76, 422 : A., ii, 756.A. Lacroix, Compt. rend., 1912, 155, 672 ; A., ii, 1182,W.T. Sclialler, Amer. J. Sci., 1912, [iv], 33, 35 ; A , , ii, 173.4 4 W. H. Foote and \V. M. Bradley, ibid., 433 ; A., ii, 568286 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.The empirical formula must therefore be written in the formNa,Al,(SiO,),, 2H20 + sEf&5205, which may be interpreted to meanthat some other molecule, possibly Na2A1,Si60,,, 3H,O, is present insolid solution, the case being similar to that of nephelite. Excess ofsilica has also been noticed in an analcite from Vesuvius.49Among other zeolite analyses may be noticed one of Zuumontitefrom Heimbach, near Oberstein, where the mineral occurs in largewhite to reddish-white crystals, and three of phdZipsite61 from tbleucite-basanite of the Eulenberg, near Leitmeritz.The latter areremarkable as showing wide divergences in composition.Meteorites.Some interesting speculations on the origin of meteorites, moreparticularly of those exhibiting chondritic structure, have beenmade by L. L. Fermor.52 He believes that the material of suchstony meteorites was once part of a garnet eclogite existing a t aconsiderable depth below the surface of some primeval stellar body.The sudden diminution of pressure which took place on the disrup-tion of the body caused the garnet to liquefy with increase ofvolume, and the subsequent rapid fall in temperature lead to therecrystallisation of the material in radial aggregates of enstatiteand olivine, so characteristic of the meteoric chondules. He findssupport for this theory in evidence he has collected for the exist+ence a t a considerable depth below the terrestrial surface of a zoneof rocks rich in garnets.An important general investigation of an experimental characteris that carried out by F.Berwerth and G. Tammannu on thenatural and artificial ‘(burnt” zone of meteoric iron, and thebehaviour of Neumann’s lines in heated kamacite. The latter areprobably due to twin-lamellz revealed on etching, and if this viewis correct the lines ought to be weakened or disappear altogetherwhen the kamacite is annealed. This has actually been observedto be the case when plates of the Mount Joy meteorite were heatedat about 870O. In the case of the AvCe meteoric iron, the lines arenot visible in the outer layer of granular kamacite, but on goinginwards a layer of irregular structure is met with, containing frag-ments of the lines, which in turn gives place to the normal internalstructure.An artificial burnt zone exhibiting similar appearancescan be produced by heating to incipient fusion sections c.f kamacitewrapped in asbestos paper.49 S. J. Thugutt, Centr. Mi%., 1911, 761; A., ii, 176.50 V. Diirrfeld, Zeitsch. KryYt. Min., 1912, 50, 257; A., ii, 359.51 J. E. Hibsch and A. Scheit, Tsch. Min. Mitt., 1911, 30, 469; A., ii, 774.52 Asiatic Society of Eengal, 1912, Sept. 4.53 Zeitsch. anorg. Chem., 1912, 75, 145; d., ii, 652.For other analyses of zeolites, see A., ii, 57, 175, 176.Abs. Nature, 1912, 90, 213MINERALOGICAL CHEMISTRY. 287The question as to the possible cosmic origin of certain glassybodies from Oberkaunitz continues to excite interest.Weinschenk,one of the principal upholders of this view, classed them as tektite~,6~and based his opinion partly on the abnormal composition of theobjects. It has, however, been pointed out recently55 that frag-ments of an old glass vessel, probably of Venetian origin, haveapproximately the same composition as the Oberkaunitz tektites,and exhibit the same sort of surface markings as the glasses fromHuttenberg described by Weinschenk. It would 'appear, therefore,that the composition and surface markings of these bodies cannotbe regarded as affording evidence of their cosmic origin.Among individual meteorites we may note the following :Arabia.-A meteorite reported to have fallen in the El Hejazregion of Arabia in the spring of 1910 has been examined byJ.Couyat.66 It consists essentially of olivine, enstatite, and clineenstatite, with a small quantity of felspar, troilite, and nickel-iron.Brittany.-S. Meunier 57 has called attention to two meteorites,both of which fell in Brittany in recent times, but which have notas yet been properly examined. One fell on June 30th, 1903, inthe Canton of Rochefort-en-Terre, Morbihan. It consists princi-pally of olivine with a certain amount of pyroxene and minutegrains of nickel-iron. Chondrules are very rare.The other fell on July 4th, 1890, a t Saint Germain-du-Puel, Ille-et-Vilaine. The stone weighs 2-74 kilos., and has a very remark-able shape, for when pieced together with a fragment broken offfrom it before reaching the ground and found 3 kilometres away,it forms a plate 30 cm. long, 15 cm. wide, and only 5 cm. thick.From a study of the surface markings it is, moreover, evident thatthis plate must have traversed the atmosphere with one of its flatfaces foremost! An examination of a thin section shows that thismeteorite is rich in chondrules of enstatite dispersed through agroundmass composed of olivine, pyroxene, and grains of nickel-iron.El A'akhZa.-A shower of meteoric stones fell near the village ofE l Nakhla El Baharia in the Nile delta on June 28th, 1911. Thestones, which are coated with a glossy black skin, consist of a friableaggregate of crystalline grains, of which the larger part, about75 per cent., is diopside, the rest being mainly a brown olivine. Ina thin section a certain amount of interstitial matter can be seenbetween the grains, resolved by the microscope into an aggregateof felspar laths with augite and magnetite. No metallic iron is64 Ann. Report, 1911, 267.66 A. Rzehak, Centr. Min., 1912, 23.68 Compt. rend., 1912, 155, 916; A . , ii, 1183.67 Ibid., 154, 1739 ; A., ii, 776288 ANNUAL REPORTS ON THE PROGRESS OF CHEMISTRY.present. Three bulk analyses of the meteorite have been made byPrior,SB Pollard,sg and Meunier Go respectively, with concordantresults.Prior and Pollard agree that the composition of the diopsidemay be approximately represented as 3MgSi0,,3CaSiO3,2FeSi0, butwhilst the former has shown that the other main constituent isolivine approximating to 2Fe,Si0,,Mg,Si04, the latter has describedit as hypersthene. As Prior's identification rests on an analysis ofselected grains confirmed by a determination of the optical proper-ties, there can be little doubt as to its correctness.This meteorite approaches most nearly t o the Angrite group,but may be regarded as a new type, for which the name nakhliteis proposed.61HoZbrook.-A shower of meteoric stones took place on July 19th,1912, near Holbrook, in Navajo County, Arizona, and over 14,000separate individuals ranging in weight from 6665 grams to less than0.1 gram have been collected. The material consists of enstatite(50-60 per cent.), divine, diallage, and glass, with small amounhof nickel-iron, pyrrhotite, magnetite, and chromite. Well-markedchondrules of enstatite are present.62KroukL-A meteorite found near the place of this name in theGovernment of Minsk, Russ'ia, has been described by Gristchinsky.63It is a typical pallasite, and so exceedingly similar to the Braghinemeteorite that it seemed probable that it was really a representativeof the same fall.64 There seems, however, to be good reason forbelieving that it fell quite recently, in 1892 or 1893, and, if so, wehave the curious coincidence that two meteorites of similar com-position have fallen in the same district a t widely separated dates.Its externalappearance has been described by T. Hiki.65 Another more recentfall has also been recorded from the same country. It took placeon July 24th, 1909, and a number of stones were collected. Theseare composed of olivine and bronzite with small amounts of nickel-iron and troilite. A bulk analysis of the stone has been publishedby T. Wakimizu.660kano.-This meteoritic iron fell in Japan in 1904.A. HUTCHINSON.G. T. Prigir, Min. Mug., 1912, 16, 274.59 J. B. Pollard, Survey Department (Egypt), 1912, Paper NO. 25.60 S. Meunier, Compt. rend., 1911, 153, 785; Ann, Iteport, 1911, 267.e2 W. M. Foote, AnLer. J. Sci., 1912, [iv], 34, 437 ; A., ii, 118363 Awn. Geol. Aiin. RUSS., 1911, 13, 72.ti4 L. L. Ivanoff, i b i d . , 114.65 Ueitrage z. Min. Japnn, 1912, 4, 142(i6 Ibid., 145.See also F. Berwerth, Tsch. Mix.. Nitt., 1912, 31, 107