GEOCHEMISTRY,THE year’s literature has reflected a substantial increase in interestin almost all branches of geochemistry. There are considerableimprovements in the study of opaque ores by reflected light, whichseem destined to stimulate interest in these substances and toremedy the somewhat one-sided development of the science infavour of the non-opaque minerals. X-Ray researches on most ofthe chief mineral groups have already been published, and thereis a consequent slackening in the description of entirely new struc-tures; many of the postulates on which these have been based arenow receiving more rigorous examination, an outstanding featurebeing the better investigation of solid solutions and a clearer realis-ation of the difficulties that arise from the fact that material in solidsolution cannot be detected by the ordinary methods of X-rayanalysis.Mineral synthesis includes investigations in groups suchas the sulphides and iron ores, beside the extension of work on theoxide systems. In the description of mineral species many newnames will be found, and a welcome feature is the greater complete-ness of the descriptions and analyses; special mention may bemade of the investigation of phosphate minerals which forms partof research work assisted by Harvard University, and published inthe American Mineralogist. Many chemists have obtained materialsfor research from the well-known “ Ward’s Natural Science Estab-lishment,” now connected with Rochester University ; in the autumnof 1930 this valuable mineral collection was partly destroyed byfire, but fortunately much of the stock has been saved so that theinterruption in supplies may not be so serious as was at first feared.Many mineral descriptions will be mentioned in the following pages ;attention may perhaps be directed to the descriptions of the opaquesulphides, phosphates, felspars, and clays, in which considerableadvances have taken place.It has been impossible to include areview of all branches of the subject ; for many important researcheson the properties of minerals, rock analyses, etc., reference must bemade to the “ Abstracts ” or to the literature.M inerqrap hy .This name seems destined to come into general use to designatethe study of minerals under the microscope by reflected light.Although the practical development of this subject has taken placemainly during the past few years, it is already clear that in it2% HALLIMOND :own sphere the subject will rival in importance metallography andthe study of transparent rock sections.Probably the mostimportant line of development in mineralogy a t the present time,its possibilities may already be gathered in some degree from theexcellent photomicrographs to be found, for example, in the currentvolume of Economic Geology. Methods of examination by etching,by polarised light in the manner initiated by J. Konigsberger, andby hardness and other tests, are rapidly being reduced to standardlaboratory practice, for which text-books are already available.Metallographers have long been accustomed to study and even tobuild up a phase-rule diagram from the microstructure of the corre-sponding alloys, and similar, though generally less adequate,attempts have been made at the more difficult task of interpretingthe microstructure of rocks in terms of the chemical data available.In the same way the present method has greatly helped in theinvestigation of the chemical history of sulphide and oxide ore-bodies.Important among these are the sulphide ores of Cobalt,Ontario, which have been studied by E. Thompson; etchingmethods are developed in detail for the nine chief arsenical minerals,and ore from the several mines is examined with special referenceto the relation between the composition and the distance from adiabase sill which is regarded as the source of the mineralisation.A.M. Bateman contributes an examination of the copper ores ofRhodesia. These are bedded sandstone or clay, with minutedisseminated grains of chalcocite, bornite, or chalcopyrite, andlying near the base of the Roan Series; oxidation is widespreadnear the surface. All the rocks show signs of heat alteration, pos-sibly by hot solutions carrying the ores. Linnaeite (Co,S,) hasbeen found in several mines; it contains innumerable minuteveinlets of other sulphides-an instance of the importance ofexamining opaque minerals by the present methods before inter-preting their analyses. Chalcopyrite occurs alone or in intergrowthswith bornite, which exhibits an anomalous anisotropic form.Chalcocite is the most important mineral; it exists in two forms,that originating above 91" being cubic; detailed study of the inter-growths suggests that the structures are of isometric form and thatmuch of the ore was deposited by hot solutions, contrary to thegeneral opinion that this ore is " supergene."H.Borchert 3 describes with many photomicrographs the etching,chemical characteristics, and association of the tellurides, for whichit is suggested that the transition point of hessite a t 150" wouldafford a " geologic thermometer."Econ. Beol., 1930, 25, 470. a Ibid., p. 366.a Jahrb. Min., BeiLBd., 1930, [A], 61, 101GEOCHEMISTRY. 285Contributions to theory and methods include an account of thediamond saw, by J. W.Vander~ilt,~ and a description of specialmethods for preparing " thinned " polished sections for examinationby either method of ill~mination.~ Accurate measurement of thereflecting power plays an important part in the identification of oreminerals; H. Frick describes the use of a reflexion photometerocular ; this instrument permits a comparison of the reflected lightwith the intensity of the incident beam, part of which is deviatedthrough prisms to the ocular. The general problem of ascertainingthe crystallographic directions in a surface under reflected light isdiscussed by K. Chudoba.7 In the case of many opaque ores tobe mentioned below, the description is accompanied by an investig-ation by mineragraphic methods, which may now be regarded asessential in all but the simplest cases.Xynthesis and Decomposition.Among the oxide systems that for wollastonite-anorthite-pyroxenehas been determined by L.Koch.8 Quickly cooled melts werestudied optically ; the resulting triangular diagram is of fairlysimple character, complicated by the separation of the two formsof CaSiO, and of the compound 5Ca0,2Mg0,6Si02 in a narrowfield. This system is of great technical importance for blast-furnaceand similar slags, to which reference is made. N. L..Bowen, J. F.Schairer, and H. W. V. Willems9 have investigated the ternarysystem Na,SiO,-Fe,O,-SiO,, by the method of quenching. Acmite,one of the three ternary compounds that crystallise, decomposeson melting, yielding hzmatite; the sinking of these heavy crystalswould yield a great variety of residual melts according to the extentof the differentiation.The lowest eutectic is rich in silica andcrystallises below 800", so that quartz is formed directly from themelt, even in the absence of mineralisers.For the study of ores much interest centres in the sulphide reac-tions, and a considerable body of research on that subject is nowin progress. Sulphide replacement has been studied experimentallyby J. C. Ray.lo Bornite forms finely divided graphic structureswith chalcocite, and these can be " dispersed " to a uniform textureby heating to 150" in balsam, while with steam this temperature wasbrought down to 100". Vessels of Pyrex glass were next used atloo", and by the introduction of reagents a number of metasomaticreactions were accomplished ; the resulting structures are illustratedby photographs in reflected light.J. D.H. Donnay, {bid., p. 270.Centr. Min., 1930, [A], 14.Econ. Geol., 1930, 25, 222.Jahrb. Min., Bed.-Bd., 1930, [ A ] , 61, 31.* Jahrb. Min., Bei1.-Bd., 1930, [A], 61, 277.LI Amer. J . Sci., 1930, [v], 20, 406. lo Econ. cfeol., 1930, 25, 433286 HBUIMOND :An outstanding problem is that of the origin of the siliceous ironores of the Lake Superior region. In a valuable research, J. W.Gruner l1 shows that silica is soluble in hot distilled water to adegree not hitherto realised. Various forms of silica were heatedwith water in gold-lined bombs; at 300”, the amount dissolvedreached about 1000 parts per million, greatly in excess of the valueat 200”.Silicates did not yield so strong a solution, possiblybecause of the presence of the metal ions, Oxidised Lake Superiorores are now known to exist at depths of several thousand feet, andGruner suggests that the oxidation is due to thermal waters andnot, as hitherto supposed, to atmospheric waters. This view issupported by detailed tests on the oxidation of ferrous minerals,which takes place readily in a current of steam at 200”. Magnetiteis not oxidised so rapidly, and in some bomb experiments magnekitewas formed by the limited oxidation of siderite. The second partof the paper contains a description of the principal deposits inthe Lake Superior region; their formation is attributed to hydro-thermal reactions due to the injection of enormous basic magmasunder pre-existing iron formations.Corundum and carborundum are prepared for use as abrasives;their synthesis has been described by V.L. Eardley Wilmot.12Artificial periclase is also prepared commercially and is a valuable,though expensive, insulating material. Silica clinkers, formedduring forest fires, have sometimes been regarded as meteorites;D. T. Englis and W. N. Day l3 have analysed a variety of sampleswhich disprove this mode of origin. F. Machatschki l4 has studied“synthetic domeykite,” which appears to be a mixture of twoarsenides that yield true synthetic domeykite after melting ;algodonite and whitneyite l5 yield on fusion Cu3As and metalliccopper.Great interest attaches to the alterations produced in mineralsby heating or chemical treatment. H.Haraldsen l6 describes thechanges produced in talc on heating. 0. Tamm l7 has shown thaton prolonged grinding felspar is attacked by water, yielding analkaline solution while the particles become hydrated.Publications from the Geophysical Laboratory a t Washington l8comprise work on the oxide systems including leucite-diopside,l1 Econ. Cfeol., 1930, 25, 697, 837.12 Canada Dept. of Mines, “ Abrasives,” Pt. IV, Ottawa, 1929.l3 Science, 1929, 69, 605; A., 1929, 1418.l5 Centr. Min., 1929, [A], 371; Chem. Zentr., 1930, i, 957; A., 1017.16 Jahrb. Min., Bed.-Bd., 1930, [A], 81, 139.1 7 Chem. Erde, 1930, 4, 420; A., 316.*4 Centr. Min., 1930, [ A ] , 19.Full references to these papers are included in the postcard lists, Nos.50-53, circulated by the Laboratory during the yearGEOCHEMISTRY.287acmi t e , potassium met asilic ate, the cris t obalite liquidus, andNa20-Si0,. Vulcanicity is represented by studies on the gasesevolved in the Valley of 10,000 Smokes, Katmai, and on the CentralAfrican volcanoes. Several inorganic systems have been examinedincluding the polymorphous forms of sodium sulphate and potassiumnitrate, the ferrites of magnesium, zinc, and cadmium, and thebehaviour of nitrogen pentoxide at low pressures. Further progresshas been made in determining the elasticity of rocks and minerals lYand the physical properties of silica, and thermodynamic studiesbearing on geochemistry include work on the solutions water-ammonia and an extensive discussion of the equations governingmulticomponent systems.Two papers deal with petrology, onpacificite and the St. Pauls Rocks, and one with the Mid-Atlanticridge. Corresponding work during the preceding year is given inabstract in the Annual Report of the Director 2o for 1929.X-Rays and Chemical Constitution.For the geochemist, the silicates possess an outstanding interest,and the year has been distinguished by an unusual number of papersdealing with the chemical formulation of the silicates in the lightof X-ray research. The complete novelty and importance of theX-ray method of crystal measurement led temporarily to a quiteabnormal output of descriptive work; with the result that, forthe silicates in particular, the general examination of the structuresis now approaching completion. Valuable summaries by W.L.Bragg of this work on the silicates were mentioned in last year’sReport, and a further very complete account by the same authorhas appeared during the current year.21 This summary is of specialinterest on account of the light it sheds upon the value of the proofsoffered for the proposed silicate structures. The brief indicationsgiven make it quite clear that some of the more complex silicateshave been interpreted by means of principles which are not uniformand possess a rather alarming degree of elasticity. Thus for silliman-ite we learn that “ the substitution of aluminium for silicon willnot affect the X-ray diffraction,” and that “ the removal of oneatom of oxygen in forty appears to be tolerated without spoilingthe structural scheme ” ; in Taylor’s solution for analcite “ sixteensodium atoms must be distributed between twenty-four positionsin the unit cell.” In ultramarine, on the other hand, Jaeger has asurplus of sodium atoms, and these are disposed of by assigning themto “ wandering ” positions in the unit cell.Attention ha+s alreadyl@ Proc. Nat. Acad. Sci., 1929, 15, 713.2o Came& Inst. Wash., Year Book, No. 28, 1929, p. 67.a1 2. Kcist., 1930, 74, 237288 HALLIMOND :been drawn in previous reports to certain inconsistencies betweenthe proposed structures and the actual chemical composition of thesubstances concerned; a closer agreement is much to be desired.Future work may be expected to deal to an increasing degree withthe more difficult and debatable aspects of the subject.It wouldlie outside the scope of the present report to give details of thehighly complex structures themselves ; claims have been madethat the chemical properties of a substance can be predicted fromthe form of the space-lattice, but present achievements in thisdirection can hardly be said to have practical importance for thechemist, who will still find it necessary to determine melting pointsand solubilities by the usual methods. One aspect of the subject,however, seems likely to receive much attention from geochemists inthe immediate future; this is the question how far X-ray data canbe used to ascertain the true chemical formula of the silicates.Formulation of the Silicates.In complexity and numbers, the silicates as a class challengecomparison with the organic compounds, and many attempts havebeen made to devise corresponding chemical formule.On the intro-duction of X-ray analysis, a curious reaction set in against the useof formula? of any kind, for it was discovered that the atomicspacings showed in general no demarcation between atoms thatmight be expected to belong to neighbouring molecules. Studentsof organic chemistry had, it is true, been warned of the danger ofattributing any special physical significance to the “ bonds ” of astructural formula, and it was well known that some constitutiveproperties, such as the spectrum of the uranyl group, were presentequally in the crystalline state.Yet the anticipation that chemical“ bonds ” would be evidenced by some physical union between theatoms was so strong that attempts at formulation were very generallyabandoned; P. Groth himself was led to announce “ it is now nomore a question of the chemical molecule.” Of late years thetendency has been to resume the search for a chemical theory ofthe silicates. The absence of molecular demarcation is now knownto be very general in crystals even of the most neutral chemicalcharacter, in which there is every reason to think the atoms arechemically combined : it is difficult, for example, to believe thatthe molecules of a high explosive undergo any serious disturbanceduring crystallisation.Characteristic groups of atoms of the kindto be expected from the chemical formula have now been recognisedboth in organic compounds and in the silicates: the crystallinestructure in both classes of compound suggests that atoms combinedtogether must remain in association, but are capable of a limiteGEOCHEMISTRY. 289free movement around one another so as to assume stable sym-metrical positions in a close-packed space-lattice. The chemicalmolecules might be regarded, in a crude analogy, as readilyflexible, but riot usually subject to decomposition on entering aspace lattice.In considering the very interesting formule proposed by Machat-schki and others,Z2 it may be well to note briefly a somewhat mis-leading tendency in present-day nomenclature.The properties ofthe space-lattice have been explained in terms of many new concepts,based, of course, upon the X-ray properties of the crystal. Therehas been, however, a seeming reluctance to introduce correspondingnew terms; enthusiasm for the application of X-ray methods tochemical problems haa led those concerned to apply old-establishedchemical terms, such as “ valency,” “ ion,” “ stereochemistry,”and “formula,” in a sense quite outside their established use inchemistry. Pauling, for example, has introduced the term valencyto designate a vague and often fractional atomic property which isheld to govern the grouping of atoms in the space-lattice. Again,it has been held that the atoms in a space-lattice are in the “ ionised ”state; the term “ ion ” has consequently been quite commonlyused even in cases where the question of ionisation is not underdiscussion, and where the less debatable term “ atom ” would moreaccurately represent the concept involved.The idea of ionisationin crystals seemed at first to derive support from a well-knownestimate of the size of oxygen, due to Wasastjerna. That authorextrapolated the atomic volunies for a salt in solution so as to obtainan estimate of the volumes of the atoms after crystallisation. Inaccordance with the theories current a t the time, he represented theatoms as spheres and calculated the corresponding ‘‘ ionic ” radiifor chlorine, etc. This estimate has since been used as a basis forthe calculation of many “ ionic radii,” and P.Niggli, in the intro-duction to his latest work on the properties of binary compounds,has summarised the current position as follows : 23r‘ Now experiment shows that radii so calculated are in no wayconstant; many of the results vary according to the substancechosen for starting the calcuhtion. Again, it must not be assumedthat the practice of dividing the interatomic distance into atomicdomains is advantageous for exhibiting the relation between thecrystalline state and that of free ions. The discrepancies between2a These discussions have appeared chiefly in the pages of the Zeitschriftfur Kristdlographie, 1930,73-75, and of the Centralblatt fur Mineralogie, Abt.A, 1930. Formulae have been advanced for the contents of the unit cell in anumber of the most complex minerals ; for details, reference should be made tothese volumes.23 2.Krist., 1930, 74, 375 (somewhat condensed in translation).REP.-VOL. XXVTI. 290 HALLIMOND :calculated and observed interatomic distance, which lead to incon-stancy of the radii, may be ascribed to polarisation, deformation,contrapolarisation, structure-incommensurability, etc. ; but it isclear, to anyone who calculates the radii by way of some otherhypothesis, how much all these concepts depend upon basic postul-ates whose arbitrary nature cannot be evaded.‘‘ The consistent and comprehensive system [of atomic radii],developed by L. Pauling, H. Grimm, and especially V. M. Gold-Schmidt, covers a wide range of phenomena in crystal structure.Anyone who has reconciled himself to the fundamental postulatesmay usefully employ the system for crystallo-chemical problems ;but it must be clearly understood that the regular relationships sodescribed are in themselves no evidence for the correctness of thehypothesis.I n fact it is possible to discover the same regularrelationships, and even more extensive ones, without postulatingthis division into atomic radii, which is inevitably of an arbitrarycharacter.Niggli then discusses the relations between interatomic spacingand the nature of the elements present ; like many other properties,the spacing varies periodically with the atomic weight, and relation-ships of a general character can be traced. For this subject heemploys the name stereochemistry, but in a sense very differentlindeed from that in which the word is used by organic chemists.Lastly, to return to the subject of the present note, the wordformula * has been used to designate the contents of the smallestrepeated unit in the space-lattice.Such a group of atoms can berepresented by symbols like an ordinary chemical formula, indeedin many simple substances the two are identical. But in substanceswith more complex chemistry the two no. longer stand in anynecessary relationship. It will be convenient, in the present dis-cussion, to use the terms “ physical formula ” for the above unitgroup and “ chemical formula ” for the symbols that summarisethe composition and reactions of the compound in question.Thedifference between the two kinds of formula has given rise to muchconfusion because so many physical formulae are written withsubstitutions, like (Ca,Na), that violate the rules of valency governingthe construction of a chemical formula.The importance of the physical formula lies in the fact that it isthis, and not necessarily the chemical formula, that is obtainedwhen the structure is solved by X-ray methods. If all the pointsof a given kind in the space lattice were occupied by like atoms,the relation to the chemical formula would be simpler: the dis-crepancy arises chiefly from the fact, now well established, that* Machatschki uses the term crystallo-chemical formula.It can be done in a second way.GEOCHEMISTRY. 291atoms of similar volume may “ proxy ” for one another in thelattice; for instance, sodium may occupy the place of a calciumatom.This kind of substitution is represented in the physicalformula by the group (Na,Ca) in the same way as an isomorphousreplacement in a, chemical formula, but the two must be clearlydistinguished.Substitution over the full range implied in the physical formulawould obviously yield a number of compositions which are knownto have no stable existence : the fact is that only those physicalsubstitutions are possible in which the resulting difference inchemical valency is compensated by a change in the composition ofthe rest of the crystal. The nature of this compensation dependson the chemistry of the compound, and the physical formula mayshed little or no light on the problem.The SpineZs.-The serious limitations of the physical formula arewell illustrated by the case of the spinels, reviewed in a very interest-ing paper by F.Ma~hatschki.~~ A typical spinel has the formula(Mg,Fe)O,Al,O,. Now titaniferous spinels are known, in which achemical molecure, probably RO,TiO,, enters in solid solution ;X-ray analysis shows that the titanium occupies the place ofalum*ium, so that Machatschki writes the physical formula of thespinel group so far defined as Y Y’, (O,F),, where Y represents atomsMg,Fe,Zn, etc., and Y’ is Al,Fe,Cr,Ti, etc. But this is not all,for there are yet other spinels with a wider range of composition :a series of synthetic crystals has been prepared which are, chemicallyspeaking, solid solutions of free alumina in ordinary spinel.Alumin-ium atoms here occupy the place of magnesium, and the physicalformula must now be further simplified, so that it assumes the formY,O,, where Y now means (Mg,Fe, etc. ; Ti,Al,Cr, etc.). Machat-schki does not further pursue these developments, but it seems fairto remark that another step is probable, if not already necessary :The Y elements do not differ very widely in volume from oxygen,and if by any chance conditions should be realised in which one ofthem could replace oxygen in the space-lattice the physical formulawould undergo another, and presumably final, simplification intothe form Z, where Z might be any atom. Thus the increasing com-plexity of this series of compounds, judged from the chemicalstandpoint, is met, not by a corresponding development in thescope and diversity of the physical formula, but by its almostcomplete disappearance into the vaguest of generalities.Clearly,the X-ray analysis of such a complex group, yielding the formula%, would shed very little light upon the chemical formulae of thewell-known compounds present.24 Centr. Min., 1930, [ A ] , 191292 HALLIMOND :Mineral$.Elements.-The generally accepted theory that the gold depositsof the Rand conglomerate were formed as placer deposits has beenexamined by L. C. Graton,25 who gives a very full discussion of theevidence. On the grounds of the absence of detrital grains of goldand other heavy minerals, the fineness of the grain size, enrichmentof the top as well as the bottom of some reefs, and the prevalence ofauriferous quartz veins, he concludes in favour of hydrothermalorigin, from solutions infiltrating the conglomerate.C. D. Hulin 26describes an unusual gold vein from California, in which the ganguemineral is largely apatite. Diamond deposits on the Upper Ara-guaya River have been described by F. W. Freise; 27 and those onother Brazilian fields by A. P. L. B&im.28 Perhaps the mostfamous deposits in the world a t present are the raised beaches nearthe mouth of the Orange River in South-West Africa. These arebriefly described by A. L. Dutoit ; 29 the diamonds are concentratedalong the foot of the ascending storm beach a t the inner side of theraised beach terrace; by means of carefully contoured maps, asuccession of raised beaches has been traced, and the productivearea has been rapidly extended, so as to indicate some wider sourcethan the Orange River itself.Cz~rtisite,~~" a new hydrocarbon, has the formula C2,H,,.Thucholite 29b is interesting on account of its occurence withuraninite.Halides.-Detailed mineral analyses of the Solikamsk salt depositin Russia are given by J.V. Moratschevski; 30 N. N. Efremov andA. A. Veselovski 31 discuss the bromine content of the carnallites ;I. V. Poire 32 finds that their colour is due to iron oxide as needles,threads, and platelets. Sodium chloride and sylvite preceded theother salts, and G. G. Urazov 33 has discussed the order of crystal-lisation, which agrees with that in the quaternary system KCI-NaC1-MgCI2-H2O. Red salt from the southern United States wasalso found by J.E. Tilden 34 to contain matted tubules mingled withiron oxide ; they appear to be the remains of an organism for whichhe proposes the name Phormidium antiquum. One of the mostz5 Econ. Geol., 1930, May (supplementary volume).26 Ibid., p. 348.2 8 Bull. SOC. franp. Min., 1929, 52, 51; A . , 1930, 1016.2* Econ. Geol., 1930, 25, 653.295 Amer. Min., 1930, 15, 169.30 Ann. I n s t . Anal. Phys. Ghem., 1930, 4, 113; A., 1015.31 Ibid., p. 99; A . , 1015.82 Ibid., p. 85; A., 1015.34 Amer. J . Sci., 1930, [v], 19, 297; A., 670.27 Ibid., p. 203.29b Ibid., p. 499.33 Ibid., p. 41 ; A . , 1010GEOCHEMISTRY. 293striking occurrences of rock salt is the exposed salt plugs of SouthernPersia, described by J.V. Harrison; 35 the salt has here beenexthded on a large scale, and even forms " glaciers " that spreadoutward over the surrounding rocks.SuZphides and Xulpho-salts.-A remarkable occurrence of copperores in Alaska is described by X. G. L a ~ k y . ~ ~ The deposit is mainlychalcocite, which proves on inineragraphic investigation to be ofthe isometric (high-temperature) form. It occasionally exhibitsbanded structures which are believed to indicate deposition in acolloidal form above 90" ; this contained dissolved covellite whichseparated on cooling. Chalcopyrite, usually a vein-mineral ofrather late formation, is found in Montana 37 in a magmatic depositwhich is really a perthitic syenite composed mainly of orthoclaseand albite; platinum is present with the copper.Graphic inter-growths of the chalcopyrite and niccolite from Sudbury, Ont., aredescribed by C. Lausen,38 who concludes that the first deposit ofgersdorffite and quartz was shattered, with the introduction ofmaucherite followed by niccolite ; chalcopyrite then replaced theniccolite. The word " graphic " has been used to describe a varietyof inter-penetrant structures, due variously to simultaneous crystal-lisation from the melt, to " unmixing '' of a solid solution and toreplacement ; in the present case, although it is known that the twominerals are mutually soluble at high temperatures, and " unmix "on cooling, the author holds that the structures are due toreplacement.W.H. Newhouse and G. H. Flaherty39 have undertaken a com-parison between various types of the metamorphic copper ores ;these offer one of the most difficult geochemical problems, for it ishard to distinguish between deposits altered by the metamorphismand those due to chemical replacement of different mineral bandsin the schist.D. F. Hewett and R. N. Eove40 describe veins exhibiting thesequence rhodonite, alabandite, and rhodocroisite, the last in partreplacing the earlier minerals. The position of molybdenite in thesequence of deposition is dealt with by A. F. Buddington,P1 whodescribes a pegmatite from Alaska, in which sulphides replacesilicates in the sequence pyrite, sphalerite, pyrrhotite, chalcopyrite,molybdenite, followed by a zeolitic phase.W. F. Foshag andM. N. Short 42 have proved by mineragraphic examination t h a t amineral from Czechoslovakia with the composition of arsenoferrite,36 Econ. Geol., 1930, 25, 737. 35 Quart. J . Geol. SOC., 1930, 86, 463.37 Bull. U.S. Geol. Survey, 1929, 811, [A], 50.38 Econ. Geol., 1930, 25, 356.40 Ibid., p. 36.39 Ibid., p, 600.4 1 Amr. Min., 1930, 15, 428. 41 Ibid., p. 197294 HALLIMOND :FeS,, is isotropic; arsenoferrite is thus a true species distinct fromlollingite. A similar investigation of an arsenical ore from Silesiais given by H. S~hneiderhohn.~~ Violarite and other nickel sulphideshave been investigated by M. N. Short and E. V. Shannon,44 whofind that violarite from Sudbury, Ont., is identical with a nickelsulphide observed in several other ores with the formula (Ni,Fe),S,.The well-known sulphide minerals of Hungary have been describedby S.K o ~ h , ~ ~ who gives a method of aiialysis with descriptions ofmany bismuth and tellurium minerals. Nagyagite (analysed),proustite, and xanthoconite are described by L. T ~ h o d y . ~ ~ Othercomplex sulphides include miargyrite from California (E. V. Shan-n ~ n ) , ~ ' antarn~kite,~~ a new gold silver telluride from the PhilippineIslands, fiiloppite, 3PbS,4Sb,S3, a new mineral from Hungary (I. deFin&ly and S. K o ~ h ) , ~ ~ and ramdohrite, Ag2S,3PbS, a new mineralfrom Bolivia, described by F. Ahlfeld.50 D. Guisen 51 has made amineragraphic study of the sulpharsenites from the Binnenthal.Oxides.-Much interest has centred in the occurrence of cassiterite.The question how far the Bolivian tin deposits are due to oxidationof sulphides continues to be debated; J.T. Singewald 52 holds thatthe greater part is hypogene. Details of the crystal habit of severaltypes of cassiterite are given by F. Ahlfeld,53 who gives lists of theoccurrence of Bolivian sulphides and concludes against the down-ward migration of tin oxide. After quoting historical records,J. Hulmaier s4 gives an elaborate description of the crystal habit ofcassiterite from the chief known localities. An instructive exampleof the origin of primary tin veins is recorded by D. R. D e r r ~ , ~ ~ whodescribes a pegmatite in which the segregation of cassiterite-bearingstreaks has occurred towards the hanging wall during consolidationof the rock.Silica.-The name lechtelierite is proposed for natural fusedsilica, of which a remarkable occurrence is described by A.F.Rogers; 56 a t Meteor Crater (Coon Butte), Arizona, layers of silicaglass up to 6 inches in thickness are found a t the bottom of the43 Chem. Erde, 1930, 5, 385; A., 733.44 Amer. Min., 1930, 15, 1 ; A., 1551.4 5 Udn. Koh. Lapok, 1929, 62, 425 ; Chent. Zentr., 1929, ii, 2872 ; A., 1930,4 6 Gentr. Min., 1030, [A], 117.4 7 Proc. U S . Nut. Mus., 1929, 74, No. 21; A., 1930, 1397.4 8 Philippine J . Sci., 1930, 41, 137.49 Min. Mug., 1929, 22, 179; A., 1930, 189.bo Centr. Min., 1930, [ A ] , 365.5l Bull.Acad. Sci. Rournaine, 1929, 12, No. 7-10, 44.52 Econ. Qeol., 1930, 25, 91, 211.54 Jahrb. Min., Bei1.-Bd., 1930, [A], 61, 403.65 Emn. Gwl., 1930, 26, 146.734.53 Ibid., p . 546.s6 Arner. J. Sci., 1930, [v], 19, 196GEOCHEMISTRY. 295depression ; these are attributed to fusion of the sandstone on impactof the meteorite. Agate has been studied by H. he in^,^' who givesanalyses of the separate layers in flints from the chalk; artificialcolouring affected the layers containing most opal. F. A. Burt 58describes capsular silica from Texas. Quartz has been examinedby R. Wei1,S9 who finds that sections cut perpendicular to the axisindicate the existence of two types distinguished by optical proper-ties and etch-figures. Among other oxides, the emery deposits a tPeekskill are discussed by J.L. Gillson and J. E. Kama,60 whoregard the deposits as due to the reaction of magmatic solutionson the already consolidated margins of a norite mass, and on thesurrounding metamorphosed schist, which is stated to have anacid composition. Cobalt minerals, including a new mineralstccinierite, (Fe,Co,Al),0,,H20, from Katanga, are analysed byV. Cuvelier.61 Chromite is found in its purest form in meteorites;the ore-mineral varies widely in composition (L. W. Fisher).62E. S. Sampson and C. S. Ross 63 describe occurrences which theybelieve to indicate that chromite can be deposited at a late stagein mineralisation. Boehmite, A1,0,,H20, occurring as minutecrystals in bauxite, is shown by R. Hocart and J.de Lapparentto be homologous with lepidocrocite. Titanium in bauxite is shownby the latter 65 to occur always as a dust of highly refractive titaniumminerals. Among the oxides of iron, mention may be made ofpisolitic iron ores from Wiirttemberg, which are regarded byE. A. Ehmann 66 as " fossil laterites," while M. Solignac 67 describesa limonite oolite from Tunisia with pellicles of phosphate. Man-ganese oxide is sometimes deposited along with limonite by springwaters, but there is usually a tendency for one or other mineral topredominate ; examples are described by (Frl.) G. Schrenckenthal **in the cementation of gravels from the Marchfeld, while H. Lasch 69gives an account of manganiferous nodules dredged from the bed ofa lake in Upper Austria.Details of the oxides of manganese, withtheir occurrence and commercial uses, are given by E. Donath and67 Chem. Erde, 1930, 4, 501.58 Amer. Min., 1929, 14, 222; A., 1930, 187.69 Compt. rend., 1930, 191, 270; A., 1155.6o Econ. Geol., 1930, 25, 506.61 Natuurwetensch. Tijds., 1929, 11, 170; A., 1930, 188.62 Amer. Min., 1929, 14, 341; A,, 1930, 570.63 Econ. Qeol., 1930, 25, 219.64 Compt. rend., 1929,189, 995; A., 1930, 189.e6 Ibid., 1930, 190, 1312; A., 886.6e Chem. Erde, 1930, 6 , 117; A., 1397.e7 Compt. rend., 1930, 191, 107; A., 1166.66 Chern. Erde, 1930, 6, 51; A., 1398.b9 Tsch. Min. Petr. Mitt., 1930, 40, 294; A., 448296 HALLIMOND :H. Leopold.70 Magnetite has been found by E. L. Perry 7 l in theunusual form of fibrous veins, with granular magnetite a t the centre ;these occur in serpentine and are believed to be due to the replace-ment of asbestos.Jasper 72 containing magnetite and haematitehas been described from the metamorphic iron ores of Wyoming.Silicates.--Fibrous emerald-green actinolite (smaragdite), de-scribed by E. I I a r b i ~ h , ~ ~ occurs with chromite and magnesite inserpentine from Serbia. Anthophyllite fibre from Californiadescribed by J. I>. Laudermilk and A. D. Woodford 74 proves t ocontain 7.4% Na20 and is thus a new variety; it is fusible, butresists acid. Reference may be made here to the asbestos (chryso-tile) of Shabani, South Africa, which has been described by F. E.Keep.75 Another amphibole, blue-green in colour, from theMinnesota iron formation, is described by S.Richarz ; 76 it contains11-15y0 A120,, 7.92% Pe203, 1.67% Na20 ; this composition liesoutside the amphibole formulae recently advanced by Warren andPauling, and to meet the difficulty two new additional constituentformulz are proposed by Winchell.Spodumene deposits in Dakota are described by G. N. S ~ h w a r t z , ~ ~while C. Palache, S. C. Davidson, and E. A. Goranson 78 describe thehiddenite deposit of N. Carolina, which they regard as an exampleof pegmatitic mineralisation in three successive stages, the secondpegmatite injection carrying the lithia minerals, which are alsofound in cavities in the gneiss resembling Alpine clefts.Hypersthenisation and the chemical transformations in silicateminerals in general are discussed by D.GuirnarPe~.~~Olivine from Vesuvius, of very unusual composition, is describedby R. Koechlin ; 8O the crystals approximate to fayalite in propertiesand may represent an iron-rich member of the olivine series. Ananalysis by F. Schwartz of massive white beryl from the S. Tyrol isgiven by E. Dittler,81 and the same mineral has been found in Mainein radial aggregates up to 18 feet in length.82 Euclase from Italy,described by A. C a ~ i n a t o , ~ ~ resembles that from Brazil ; analysisconfirms the formula 2Si02,A1,03,2Ba0,H20.70 ( 6 Der Braunstein u. seine Anwendungen ” Stuttgart, 1929.71 Amer. J . Sci., 1930, [v], 20, 177.72 Bull. U S . Geol. Survey, 1929, 811, [DJ.7 3 Tsch. Min. Petr. Mitt., 1929, 40, 191; A., 1930, 57.74 Amer.Min., 1930, 15, 259.75 Third Empire Min. Congr., April, 1930.i 7 Econ. Geol., 1930, 25, 275.79 Ann. Acad. Brasil. Sci., 1930, 2, 1 ; A., 1156.80 Centr. Min., 1930, [ A ] , 375.81 Tsclz. Min. Petr. Mitt., 1929, 40, 188; A., 1930, 57.8? E. K. Geclney and H. Berman, Amer. Min., 1930, 15, 81.83 Atti R. Accad. Lincei, 1929, [vi), 10, 656; A., 1930, 445,‘e, Amer. Min., 1930, 15, 65.7 8 Amer. Min., 1930, 15, 280GEOCHEMISTRY. 297Garnet occurs in the Adamello Mountains in reddish-browndodecahedra, in composition mainly grossularia, and associatedwith olive-green vesuvianite ; analyses and physical constants forboth minerals are given by C. G ~ t t f r i e d . ~ ~ An unusual vesuvianite,with 9.20% of BeO, is described by C.Palache and L. H. Bauer.sbAnother garnet, from Avonda'le, Pa.,85a is shown to be a memberof the almandite-spessartite series. F. Zambonini and A. Ferrari 86discuss the crystalline structure and formula of cancrinite; andB. Z. Kolenko 87 describes the distribution of orthite in the Trans-baikal region. Samarskite from New Mexico, analysed by F. 1,.Hess and R. C . Wells,88 is believed to have been formed in twogenerations at different geological periods.A new silicate from New Zealand, named arneletite, is described byP. Marshall : 89 it appears to be a member of the nepheline groupand occurs in phonolite in minute crystals and grains that are readilystained by silver nitrate.Sapphirine from Italy has been analysed by H. P. Cornelius andE.Dittler.*o Steatite from Bavaria, described by F. De~bel,~l hasbeen formed by the replacement of quartzite. Highly aluminousaltered shales near Postmasburg, S. Africa, contain the interestingminerals diaspore, kaolin, leverrierite, and zunyite ; the last isdescribed by L. T. Nel and L. J. Spencer,92 who discuss the com-position in the light of analyses by J. McCrae and H. G. Weall.Gillespite, FeBaSi,O,,, occurs with celsian and hedenbergite, forwhich composition and properties are recorded by W. T. S ~ h a l l e r . ~ ~Scazotite, a new mineral from Co. Antrim described by C. E. T i l l e ~ , ~ ~occurs in vesicles in a hybrid rock formed by the action of a doleriteintrusion upon chalk; it is allied to spurrite, and analysis byM.H. Hey agrees with the formula 6Ca0,4Si0,,3C02.M. H. Hey 95 has investigated the variation of optical propertieswith chemical composition in the rhodonife-busfamite series. Theminerals are all anorthic, but exhibit variations in the facility ofcleavage; density and refractive indices are plotted direct, and itis shown that at 30 mols.% of CaO there is a change in optical sign84 Chem. Erde, 1930, 5, 106. 85 Amer. Min., 1930, 15, 30; A., 1551.85a Ibid., p. 40. Atti R. Accad. Lincei, 1930, [vi], 11, 782; A., 1397.8 7 Bull. Acad. Sci. Leningrad, 1929, 243.Amer. J . Sci., 1930, [v], 19, 17; A., 316.8D Min. Mag., 1929, 22, 174; A., 1930, 189.So Jahrb. Min., Bei1.-Bd., [ A ] , 1929, 59, 27; Chem. Zentr., 1929, ii, 1640;9l Chem. Erde, 1930, 5, 87.O4 [With M.H. Hey] Min. Mag., 1929, 22, 222; A., 1930, 569.9 5 Ibid., p. 193; A., 188.A., 1930, 316.s2 Min. Mag., 1930, 22, 207; A., 570.Amer. Min., 1929, 14, 319; A., 1930, 670.K 298 HALLIMOND :which is taken as a convenient division between the two mineralsforming the series.Chabazite has been shown by Y. Tanaka and M. Nakamura 96 toundergo a continuous dehydration on heating up to about 1000" C.It has no adsorptive power even when dehydrated. Heulandite hasbeen studied by P. Gaubert.97 Crystals occurring at N. Burgess,Ontario, have been identified by R. P. D. Graham and H. V. Ells-worth 98 as cenosite, one of the interesting group of silico-carbonates.Fezspars.-A very detailed examination of the moonstones hasbeen contributed by E.Spencer,g9 who has confirmed the observ-ation that the schiller and microperthitic structures are destroyedby heating to about 1050". He h d s that lamellar albite is selec-tively attacked by water and carbon dioxide under pressure, whichmay explain the fact that in some of the natural specimens albite hasbeen completely removed. These results confirm the general viewthat the peculiar structure of moonstone is due to the separation oncooling of the potash and soda felspars, which are completelymiscible in the solid state at high temperatures. Several analysesare given, which lead to certain modifications in the equilibriumdiagram for these compounds. The peculiar optical properties ofmoonstone have also been discussed by A. L. ParsonsYgga withspecial reference to the material from Ontario.Potash felspar apparently exists in dimorphous forms, corre-sponding with orthoclase (monoclinic) and anorthoclase (anorthic).K.Chudoba has examined the well-known felspar from the trachyteand xenoliths of the Drachenfels and finds that both are anorthic;for this variety he proposes the name sanidine-anorthochse.The occurrence of potash in the soda-lime felspars is now commonly taken account of, but D. Beliankin2 points out that otherminor constituents cannot be neglected. In a chemical investigationhe shows that iron may be present up to 2-3%, whilst barium isoften found in the acid felspars : the analyses in certain cases cannotbe reconciled with existing theory. Very pure adularia from Japanhas been analysed by K.set^,^ and H. S. Spence gives analyses ofalbite and microcline in il description of the pegmatites of Ontarioand Quebec, where felspar crystals up to 30 feet in length havebeen found. F. C. Phillips 5 discusses the pericline twinning of96 J . SOC. Chem. Ind. Japan, 1930, 33, 274.97 Bull. SOC. franc. Min., 1929, 52, 14.Ss Min. Mag., 1930, 22, 291; A., 1397.99n Amer. Min., 1930, 15, 93.Bull. Acad. Sci. U.S.S.R., 1929, 571; A., 1930, 57.J . Petr. Min. Ore Deposits, Japan, 1929, 1, 278.Amer. Min., 1930, 15, 450.Min. Mag., 1930, 22, 225; A., 570.9a Amer. Min., 1930, 15, 206.Centr. Min., 1930, [ A ] , 145GEOCHEMISTRY. 299acid plagioclase, and T. F. Barth has described the anorthites fromthe Adirondacks. Anomalies in the order of zoning of plagioclasehave been observed by K.Ch~doba.~Clays.-Much work is recorded upon kaolinite and the more acidclays. These minerals, though often minutely crystalline, are noteasy to differentiate, but a measure of success has recently beenobtained by combining accurate physical determinations with X-raymeasurements of the crystal structure.conclude that the kaolin minerals really belong to three distinctspecies : kaolinite, the chief constituent of china clay; dickite, ilname now proposed for the mineral first described from Angleseyby A. B. Dick; and nacrite, well known from Freiberg. Kaoliniteis much more strongly stained by dyes, but is otherwise very similarto nacrite, while dickite differs in crystal habit and optical properties.AII three minerals give distinctive X-ray patterns. P.Schacht-schabe19 has studied the dehydration of kaolin; the water isregained under pressure at 200"; the rehydrated mineral, which isa t first soluble in hydrochloric acid, gradually approximates inproperties to ordinary kaolinite. Kaolin from a metamorphosedash in N. Carolina is described by J. L. Stuckey ; 10 K. Set0 l1 givesanalyses of material from Korea and Japan; and S. Malkowski andM. Kowalski 12 discuss the occurrence of clays in Poland. Halloysitenodules in limonite from the Harz are described by 0. H. Erdmanns-dorffer ; l3 this mineral loses very little water up to 400", after whichit behaves like kaolin. The more acid clays, usually containingmontmorillonite, have considerable commercial importance.Theyoften result from the alteration of volcanic ashes and have thecomposition ~ 2 0 3 , 3 s i o , with a high content of loosely held water.K. Kobayashi and K. Yamamoto l4 describe the Japanese acid clay,which is an altered liparite; the dehydration curve determinedby those authors and K. Bit6 l5 differs from that of kaolin, whileX-ray diffraction lines indicate the presence of a distinctive mineral.16Bentonite from Arizona, probably formed from volcanic ash thatfell into water, is shown by V. T. Allen l7 to consist chiefly ofmontmorillonite, while E. S. Larsen 1* also describes tuffs fromAmer. Min., 1930,15, 129.A w r . Min., 1930, 15, 34; J . Amer. Ceram. SOC., 1930,13, 151; A,, 560.51 Chem.Erde, 1930, 4, 395; A., 315.l1 J . Petr. Min. Ore Deposits, Japan, 1929,1, 179; A., 1930, 570.l2 Tram. Ceram. SOC., 1930,29, 142; A., 1397.Chem. Erde, 1930, 5, 96; A., 732.l4 J . SOC. Chem. Id. Japan, 1929, 32, 174; A., 1930, 316.l6 Ibid., p. 297; A., 316.1e N. Kameyama and S. Oka, ibid., 1930, 33, 29, 92; A., 448, 1017.l7 AWW. J . Sci., 1930, [v], 19, 283.C. S. Ross and P. F. Kerr' Centr. Min., 1930, [ A ] , 145.lo Amer. Min., 1930, 15, 10.Bull. U.S. Geol. Survey, 1929, 811, [B], 89300 HALLIMOND :Colorado altered to bentonite, and F. Tucan 19 describes a similarsilicate having a continuous dehydration curve, from Allchar inSerbia. Nontronite, which has been regarded as ferric kaolinite,appears to belong with the present group, for materials fromBavaria *O and from Pontevedra 21 both show continuous dehydr-ation a t low temperatures and approach the composition R20,,3Si0,.Another member of the group, with 7% of ferrous oxide, nearbeidellite in composition, is described by I.J. Mickey.22Phosphates.-Near Fairfield, Utah, phosphate nodules from lime-stone have yielded a remarkable series of minerals described byE. S. Larsen and E. V. Shannon.23 Wardite,2Na20,Ca0,6A1,03,4P205, 1 7H20,is shown to be a good species; variscite and pseudowavellite arecommon. New species are deltaite, 8Ca0,5Al2O3,4P2O5, 14H20 ;dennisonite, 6CaO,Al2O3, 2P205 ,5H20 ; dehmite,14Ca0,2 (Na,K),O ,4P205 ,3H20,C02,also described from Dehrn with crandallite, Ca0,2A120, ,P20, ,GH,O ;lewistonite, 15Ca0, ( K,Na),0,4P205, 8H20 ; englishite ,4Ca0,K20,4A120,,4P205,14H20 ;millisite, 2Ca0,Na20,GA120,,4P205, 17H20 ; lehiite,5Ca0 , ( Na,K),0,4A120,, 4P20,, 1 2H20 ;gordonite, Mg0,A1203,P205,9H20.These species are identified bytheir distinct physical properties, and there are many other sub-stances not yet fully described. Another set of phosphates,described by H. Berman and F. A. G ~ n y e r , ~ ~ occurs in pegmatitesa t Poland, Maine ; amblygonite replaces felspar ; analyses are givenof lithiophilite, 2(Mh,Fe)0,Li20,P,05 ; reddingite,3 (Mn ,Fe) 0 , P20 , 3H20 ;dickinsonite , 7 (Mn,Fe) 0,2 (Na, ,K2 ,Ca) 0 ,3P205 , H,O ;(Mn, Fe)O , 2Ca0 , P205, 2H20 ; landesi t e (new sp . ) ,3Fe20, ,20Mn0,8P205 ,27H20.f airfieldite ,Other phosphates described include lazulite from Chittendcn,Vermont ; 25 collophane and variscite (Styria).26 H.R. von Gaert-ner 27 examines natural and artificial pyrochlore by X-rays. Theartificial substance is cubic, but natural pyrochlore is " metamict "and only assumes the cubic structure on ignition. The new mineralbismutotanhlite, Bi20,,Ta205, is described by E. J. Waylnnd and1920212223242 62 7Bull. SOC. franc. Min., 1929, 52, 42; A., 1930, 1156.W. Noll, Chem. Erde, 1930, 5, 373; A., 733.I. P. Pondal, Arq. Seminario Est. GaZegos, 1929, 2, 9 ; A., 1929, 1418.Centr. Min., 1930, [A], 293.Amer. Min., 1930, 15, 303.Ibid., p. 375.F. Machatschki, Centr. Min., 1929, [ A ] , 321.Jahrb. Min., Bed.-Bd., [ A ] , 1930, 61, 1.26 Ibid., p.338GEOCHEMISTRY. 301L. J . Spencer.28 The mineral occurs in a pegmatite in Uganda, incrystals up to several pounds in weight ; in composition it corre-sponds with stibiotantalite.Seamunite, a new mineral, has the interesting composition3Mn0,(B,03,P20,),3H,0; it, is described by E. H. Kraus, W. A.Seaman, and C. B. S l a ~ s o n , ~ ~ from Michigan. It is apparentlyreddingite with part of the P,O, replaced by B203.Carbonates.-J. Romieux30 has made a detailed study of thedistribution of carbonates in the mud of Lake Geneva. Recentalgal limestones from S. Australia are described by D. Mawson,31and A. L. Mathews 32 concludes that the ooliths of Great Salt Lakeform a t the water’s edge and grow by evaporation of capillary wateras they are driven inland by the wind, for they are sometimes zonedwith soot.S. Mizgier 33 shows that lublinite is identical with calcite.Structures have been proposed for alstonite and barytocalcite,34and analyses are given for gaylussite, nesquehonite, and probertite.FeS04,2ZnS0,, 18H,O,is described by C. A ~ ~ d r e a t t a . ~ ~ (Miss) J . M. Sweet 36 gives anaccount of the occurrence of barytes in Great Britain, and thegeology and chemistry of gypsum in New York are discussed byD. H. Ne~land.~’ Uraninite 38 from Villeneuve, Quebec, yields avariable lead ratio, depending upon the degree of alteration; R. C.Wells 39 gives an analysis of pitchblende occurring with gold in acalcite vein from Chihuahua, Mexico.Mineral Springs.-Space will not permit detailed reference to thelarge output of records for mineral springs.American localitiesinclude N. Carolina,40 Arkansas hot springs,41 and oilfield water inAlberta; 42 data are given for the manganese content of theMississippi River.43 Physical constants, etc., for Italian springsSulphates, etc.-Bianchite, a new white mineral,2 8 Min. Mag., 1929, 22, 185; A . , 1930, 188.2s Amer. Min., 1930, 15, 220.30 Arch. Sci. phys. nut., 1930, 12, 202; A., 1155.31 Quart. J. Geol. SOC., 1929, 85, 613; A., 1930, 315.32 J . Geol., 1930, 38, 633.33 2. Krist., 1929, 70, 160; Chem. Zentr., 1929, ii, 544; A., 1930, 188.34 Centr. Min., 1930, [A], 220, 321.35 Atti R. Accad. Lincei, 1930, [vi], 11, 760; A., 1397.36 Min. Mug., 1930, 22, 257; A., 1156.3 7 New York State Mus.Bull., No. 283, 1929.38 Amer. Min., 1930, 15, 455.3g Ibid., p. 470.40 E. E. Randolph, J . Elisha Mifchell Sci. SOC., 1928, 44, 7 0 ; A., 1930, 187.4 1 Ind. Eng. Chem., 1930, 22, 633.43 Trans. Canad. Inst. Min. Met., 1929, 32, 316.43 Science, 1930, ‘71, 248302 HALLIMOND :are furnished by D. Marotta and C. S i ~ a , ~ ~ R. Nasini and E. Bova-lini,45 and for Sardinia by E. Puxeddu and G. Sanna.46 AtC h o ~ s s y , ~ ~ France, the medicinal water contains arsenic ; tadpoleskept in the well-water showed an increased arsenic content, butthis was not so marked when they lived in the bottled water.Other European localities include Upper Checkya ( Caucasus),48Zagreb 49 district, and Lower Kostrivnica, Jugoslavia. 5O Hydrogen-ion concentration has been determined by M.C. PotterY5l while0. Baudisch and H. von Euler 52 discuss the phthalein reaction inrelation to the state of combination of the iron present. Estimatesof the rarer elements have been made spectroscopically on the waterof Cambres by A. P. F ~ r j a s , ~ ~ and radioactivity determinations byV. Vernadsky 54 (deep springs in Russia) and others. Colorimetricdeterminations of uranium content on water from Caria, Portugal,are due to H. de C a r ~ a l h o . ~ ~ 0. W. Rees 56 considers that silicain natural-water analyses should be taken into account as an acidradical SiO,.Distribution of Iodine.-Minute amounts of iodine have beenmeasured in air, dew, in various food-stuffs, and in soils and waters ;a survey of the quantity available from these sources a t Salta(Argentine) 57 indicates that the average daily intake of iodine perperson is below 0.04 mg. and is inadequate.This is primarily dueto lack of iodine in food-stuffs, which compare unfavourably withthose in non-goitrous districts, even the sheep’s thyroid glandshowing corresponding deficiency. Iodine surveys are also reportedfrom N. and S. Carolina 58 and Nebraska.59 Sea-water examinedby Winkler’s method60 contains only a small amount of iodine,and the content varies little with the depth. Coal heated withalcohol and potassium carbonate in an autoclave yields a filtrate44 Ann. Chim. Appl., 1929, 19, 529; A., 1930, 448.4 5 Ibid., 1930, 20, 56, 91; A., 569, 731.4 6 Giorn. Chim. Id.Appl., 1929, 11, 438; A., 1930, 187.47 Compt. rend., .1930, 190, 1133.49 G. Janehek, Arhiv Hemiju, 1929, 3, 178; A., 1930, 187.50 Bull. SOC. Chim. Roy. Yougoslavie, 1930, 7, Reprint.51 Nature, 1930, 126, 434; A,, 1396.52 Biochem. Z., 1929, 212, 140 ; A., 1929, 1417.53 Compt. rend., 1929, 189, 703; A., 1929, 1417.54 Ibid., 1930, 190, 1172.5 6 Ind. Eny. Chem. (Anal.), 1929, 1, 200; A., 1920, 1417.5 7 P. Mazzocco, Semana mkd., 1930, 37, 358, 364, 366, 370; A., 1015.58 J. H. Mitchell, Science, 1929, 69, 650; A., 1920, 1418; J. W. Perry,59 W. H. Adolph and F. J. Prochaska, J . Amer. Ned. Assoc., 1929, 92,6o J. F. Reith, R ~ c . t r ~ . chim,, 1930, 49, 142; A., 315.4 8 J . Appl. Chena. Russia, 1088, 1, 291.55 Ibid., 191, 95; A., 1155.J .Elisha Mitchell Sci. SOC., 1928, 44, 87 ; A., 1930, 187.2155 ; A., 1929, 1427GEOCHEMISTRY. 303which can be tested by Winkler's method ; twelve mid-Europeancoals show up to 11.17 mg. per kg. By the combustion of coal7,000,000 kg. of iodine are probably returned to circulationannually.61 Domestic and drinking waters in E. Prussia sometimesshow a high content of iodine.62Sea-wuter.-The composition of the sea near Puget Sound isdiscussed by T. G. Thompson 63 and others, who give determinationsof pn, chlorine, and dissolved oxygen. I n the North Pacific theionic ratios are constant, namely Ca/Mg 0.3212; Ca/C1 0.0215;Mg/ClO*O669. E. G. Moberg 64 discusses the hydrogen-ion, phosph-ate, silicate, and fixed nitrogen contents of sea-water. Water fromthe Red Sea 65 has a very low nitrate content, owing t o the pre-dominance of denitrifying bacteria ; in consequence, vegetation isscanty.Seasonal variations in phosphate, silicate, and nitratecontent in the English Channel G6 are correlated with outbursts ofphytoplankton. D. Ellis and J. H. Stoddart 6' describe the chemicaleffects of sulphur bacteria growing in pools.Muds.-Considerable attention has been given to the compositionof sea and lake muds. H. H. Moore 68 finds that both phosphatesand nitrogen diminish with increasing depth in the sea muds ofthe River Clyde. In Black Sea muds69 the phosphorus variesinversely with the organic content ; vanadium was also determined.In Lake Saki,70 white deposits of gypsum and sand alternate withblack clays which owe their colour to hydrotroilite.The claysreact with the salts in solution, and the deposits show seasonalvariations. Other factors are the adsorption of salts and thebiochemical reduction of sulphates; in the dried mud the latterdepends on the sodium chloride content.The Origin of Coal.-Details of the coal-forming reactions are stillkeenly debated. A. Duparque 71 suggests that the primordialdeposits were of two distinctl types, represented by spores, cuticleson the one hand and woody tissue on the other. These have thesame chemical composition, and the differences in the coals producedare assigned to secondary changes that vary according to the depth6 1 E. Wilke-Dorfurt and H. Romersperger, 2. anorg. Chem., 1930,186, 159 ;A., 449.62 H. Matthes and G. Wallrabe, Pharm. Zentr., 1930, 71, 273; A., 886.63 Pub. Puget Sound Biol. Sta., 1929, 7, 65, 119; A., 1930, 731.64 Proc. I11 Pan-Pacific Sci. Gong., 1926, (1928), I, 221 ; A., 1930, 187.65 G. Bini, Atti R. Accad. Lincei, 1929, [vi], 9, 1128.66 W. R. G. Atkins, J . Marine BioZ. ASSOC., 1930, 16, 821; A., 886.67 J . Roy. Tech. Coll. Qlasgow, 1930,2,336 ; A., 569.68 J . Marine Biol. ASSOC., 1930, [ii], 16, 596 ; A., 448.6s Bull. Acad. Sci. U.S.S.R., 1930, 206.70 P. T. Ivanov, Ann. Inst. Anal. Phys. Chem., 1930, 4, 197; A., 1015.7 1 Compt. rend., 1930,190, 1200; A., 887304 HALLIMOND : GEOCHEMISTRY.of water, shallow waters yielding anthracites, while the deepestwaters yield the boghead coals. H. E. Armstrong 72 concludes thatcoal is “ a condensed material, a natural bakelite.” G. Stad-nikov 73 discusses in detail the reactions which must have gone toform the Sumpfowy seam, a coal of intermediate character, andsuggests that the fats of the algae from which coorongite has formeclmust have been reduced by anaerobic bacteria in deep salt water,and subsequently oxidised at the surface. Continued anzrobicdecomposition would yield petroleum. The “ lignin theory ” hasbeen warmly debated. G. Stadnikov and L. Kaschtanov 74 discussthe chemical character of the compounds that form the Siberianboghead coals ; on hydrogenation the cyclic acids eliminate carbondioxide and are transposed into cyclic hydrocarbons. No phenolsare formed.Meteorites.-Material from the following localities has beenanalysed : Sandia Mts. ; Hinojo, Buenos Aires ; El Mocovi ;Cachari; Renca (San Luis); Isthilart; Piedad do Bagre, MinasGeraes. Small amounts of germanium and arsenic have beendetected.75 J. Young has studied the orientation of kamacite, 76and a general account of the composition and structure has beengiven by G. P. Merri11.77 A new iron meteorite from Carbo, Mexico,is described by C. Palache and F. A. G ~ n y e r . ~ ~A. F. HALLIMOND.72 Proc. Roy. Xoc., 1930, [ A ] , 127, 268; A., 887.73 Brennstoff-Chem., 1929,10, 477; A., 1930, 190.74 Ibid., p. 417; A., 57.T 5 J. Papish and Z. M. Hanford, Science, 1930, 71,269; V. M. Goldschmidt,Z . physikal. Chern., 1930, 146, 404.7 6 Min. Mag., 1930, 22, 383; A., 1398.7 7 Bull. U.S. Nat. Museum, 1930, No. 149; A., 1157.78 Amer. Min., 1930, 15, 388