110 ABSTRACTS OF CHEMICAL PAPERS. Mineralogical Chemistry. On the Chemical Composition and Microscopic Constitzctiom of certain PHILLIPS.* Cornish Rocks. By J. ARTHUR ‘‘ KILLAS ” is the name applied by Cornish miners to all sedimentary cleavable rocks. Their geological age has not been determined beyond that they belong to the palaeozoic era and it is believed that they are of Devonian age. They enclose five large and several smaller “islands ” of granite and are as well as the granite itself traversed by dykes of granitic and porphyritic rock called ehans by trap dykes by copper and tin lodes and by various cross-courses including Jlucans or fissures filled with clay. Typical killas is a grey bluish-grey or greenish-grey clay-slate and when weathered is brownish-yellow or buff.It is usually exceedingly fissile with the planes much contorted but is often more compact near its junction with the granite. The sections examined in the microscope by “a low power ” were magnified 60 or by a “high power ” about 400 linear. I. Killas from Polgooth Mine adit level sp. gr. = 2.60. This is a very soft slate of a light-grey colour marked in places with a darker shade or yellow tinge. By transmitted light under a low power thin sections exhibit no structure but appear as a milky-white mass enclosing moss- like semi-crystalline markings of a brownish-green and traversed by fissures filled by crystalline transparent quartz. With a high power it is found to be composed of an aggregate of minute granules intimately blended together without definite outlines and to enclose some grains of oxide of iron and apparently fragments of hornblende and some patches of a chloritic mineral.11. Killas from Polgooth Mime 80.fathoms level sp. gr. = 2.74. This specimen much harder than the above is of a grey colour strongly marked with reddish-brown. Here the microscope detected no difference excepting that the grains of oxide of iron were larger but less numerous and that there were fewer of what appeared to be broken crystals of a hornblendic mineral. The granular fragments are larger and more distinct their larger surfaces being nearly parallel with the planes of cleavage of the slate. The chloritic mineral is again very abundant and peculiar markings were observed about its margin.111. Killas from Polgooth Mine 100fathoms level sp. gr. = 2.73. At this depth it is much harder than that found at shallower levels is of a greenish-grey slightly streaked and spotted with yellow. The sections resemble those from the 80 fathoms level but contain no horn-blende and fewer chloritic patches. IV. Killas from Polmear Mir~e,40fathoms below the surface sp. gr. = 2-68. This clay slate is much contorted dividing readily in curved Phil. Nag. [4] xli 87. MINERALOGICAL CHEMISTRY. laminm with glossy surfaces bearing wavy lines resembling minute ripple marks. It is of a medium grey and slightly yellow in places. Its sections resemble those of the Polgoobh specimens. Granules of quartz are disseminated through the finely-grained matrix which derives its greenish tint from chlorite,and which is minutely divided by a system of markings made up of pairs of parallel lines,each about I 2, th of an inch long and F& th of an inch apart.V. Slate from “ Sanctzcaries ” near St. Bustell sp. gr. = 2.52. This is light grey and buff in colour and appears to be weathered. It divides with difficulty into lamine the surfaces being without polish. It is divided by headings variously coloured apparently by infiltration of water containing oxide of iron. VI. Killas from Dolcoath Mine 215fathom level sp. gr. = 2.71. This rock is exceedingly hard the cleavage imperfect and its prevailing colour dark-grey. Freshly fractured surfaces exhibit numerous minute brilliant indistinct crystals probably of some hornblendic mineral.With a low power its sections appear to be made up of transparent angular particles giving co1oUz.s with polarised light ; the greenish patches disseminated through the mass are probably chlorite. With a high power are seen black grains of magnetite and titaniferous iron and fanlike aggregations of transparent acicular crystals often diverging from a particle of oxide of iron. Similar crystals also cross each other in all directions and are probably hornblende or schorl. Mechanically embedded are rounded fragments of mica and of a semi-translucent minerd not sufficiently opaque for oxide of iron. VII. Killas from Botallack Pennsance surface near lode sp. gr. = 2.95. This is a very hard dark greenish-grey rock containing minute crystals of pyrites ; its cleavage being to a great extent obliterated by metamorphism it breaks into roughly tabular masses whose planes approximate to those of original cleavage.The low power shows an amorphous base often green due probably to chlorite and enclosing transparent crystals and crystalline patches often fringed with acicular crystals which give brilliant colours with polarised light. With a high power long slender crystals probably of apatite and minute triclinic crystals possibly of axinite are seen. VIII. Rock from Botallack 130fathoms sp. gr. = 2.82. A very dark green specimen with traces of lighter shade and no cleavage is slightly magnetic and encloses in places minute crystals of pyrites. The grains of iron oxide are more numerous than in specimens obtained nearer the surface.It contains fewer long crystals than the surface rock and is traversed by minute veins of quartz enclosing transparent acicular crystals probably of hornblende. From its physical consti- tution and the large amount of magnesia it contains it may be regarded as an impure serpentine. IX. bb Best roofing slate,” DelaboEe sp. gr. = 2.81. Whilst under a low ABSTRACTS OF CHESXIGAL PAPERS. power this date shows no distinct structure bat is thickly dotted with dark pots with a high power numerous clusters about &th of an inch in diameter of reddish-brown crystals appear. These result from the agpgation of several hexagonal plates of according to Mr Sorby’s examination more or less altered specular iron.The matrix is moreover) traversed in all directions but especially in planes parallel to the cleavage by long transparent crystals that are brilliantly coloured by polarised light. Both brown and white crystals have been formed in sit%. X. DiorzXe “ Saqctuaries,” St. Mewan. sp. gr. = 2.97. This rock is of a dark green colour verging on black is exceedingly hard and tough distinctly crystalline and magnetic. These sections exhibit nnmistak- able evidence of extensive alteration. The felspat does not generally present any distinctive characteristics although in a few instances the parallel striping peculiar to triclinic varieties was observed The rock also contains semi-transparent yellowish-brown crystals probably hornblende a green mineral of fibrous structure which is believed to be a variety of hornblende many black grains of oxide of iron some well-defined hexagonal crystals probably apatite and an abundance of a green chloritic mineral.This diorite has probably undergone much a1teration. XI “ Greenstone,” Blowing-House Hill Bt. AustelZ sp. gr. = 2.89. This stone is very similar to the “ Sanctuaries ” rock but is of a some- what duller aspect and is divided by a series of oblique cross headings,which impart to it a tendency to divide into rhomboidal masses; it is also less decidedly crystalline and exhibits a grain resembling that of some varieties of metamorphosed schist. The sections shew a compact felspathic matrix enclosing B few indistinct crystals of felspar together with large quantities of the greenish chloritic mineral observed in the St.Mewan diorite from which the greenstone differs but little in composition. The greenish mineral is arranged in approximately parallel bands and patches many of the latter appearing to be partially decomposed horhblende crystals and though retaining at their cehtre to a certain extent their original structure and colour have at the edges been transformed into chlorite or an allied mineral. The rock also conthins tmny black grains of oxide of iron and some hexagonal crystals probably of apatite. It is believed to be an altered clay-slate. XII Serpentinous rock Mennheniot sp. gr.=2*77. This is a moderately hard stone of a dark green colour has a somewhat crystalline fracture and schistose structure and is slightly magnetic.It occurs more or less intermixed with clay-slate and beds of unaltered slate are fomd interstratified with it. It exhibits numerous resinous headings many of which are coated with asbestos with fissures containing calcite. MINERALOGICAL CHIENISTRY. 113 Rmiform concretions of sapanite are frequently found in a clay app;L. rently resulting from the decomposition of the principal rock. The microsoope show-s a highly metamorphosed rock consisting of an amorphous matrix porphyritically enclosing yellowish-brown or green patches with indistinct crystalline forms evidently pseudomorphs with many grains of magnetite and crystals of what is probably schiller-gpar or diallage.XIII. Beypentine Lizard,sp. gr. = 2.99. The specimen is of a very dark green colour in places verging on black and thickly spotted with red ; it has a ooarsely granular structure is without my indication of foliation and eneloses imperfectly develaped cry staltls. XIV. Orthoclase,“ Glass nili’ne,’’ Roche sp. gr. = 2.55. This yellowish- white felspar occurs in granite containing considerable quantities of schorl and is traversed by reins of milky quartz enclosing tourmaline and cassiterite. Prof. Miller of Cambridge examined it crystallo-graphically and pronounced it to be a mono-clinic felspar. The following table exhibits the mean results of the analyses of these rocks :-H20. Si02. Ti02. PaO,. A1203 Fe203. FeO. Mn304. CaO. MgO. 1120.~~~ I. 408 60.42 -0.21 d0.83E 8.17 1-89 041 1.71 trace. 0.77 1-55 11. 3.63 63.10 trace. trace. 20.15 3.61 2.955 trace. 1-27 trace. 0.95 3-18 111. 3.265 60.915 trace. -20.78 13.415 4.92 trace. 1-62 -0-93 9-08 PQ8S IV. 6.58 49.265 trace. -18.00 12-68 8.56 082 2.13 trace. 0*56E 0.745 V. 6.16 53.30 trace. trace. 21-72 6.015 428 -trace 075 2-92 4195 VI. 1.15 67-315 0.13 -20-841 2-883 1.66 -2085 trace. 0.59 3-37 iulphur. VII. 3.125 40.21 015 0.66 2401 4\21 11-29 trace. 41@ 6-58 1.67 3-53 VIII. 11.09 32.98 trace. trace. 1673 ?a25 13.71 twe. 4-90 11-52 0.73 0.625 IX. 4.61 58-30 0.23 trace. 21-59 7-055 257 -039E 1.091 2.45 1.135 M~0.p X. 0.80 47.56 trace. 011 17.16 13.06 . 9.30 trace. 411 tram. 2-30 5.45 XI. 1.00 47.505 trace. tram.17.00 11.75 10.71 0.41 6-28 trace. 2.89 2.545 cr203 XII. 1056 38-70 trace. trace. 1’7.59 15.04 4-56 0.14 498 6-00 trace. 0845 XIII. 15.52 3@72 -2.991 1.905 5.07 0.08 trace 3L56; 0.32 0.765 and 0.29NiC XIV. 0.665 65.165 -19.08 0.50 -1.622 trace. 10.37 2-40 X likewise contains traces of sulphur ;XI1 and XIII traces of an oxide of manganese. In the estimation of silica in the foregoing apalyses the following method was adopted. The fused mixture after treatment with hydro- chloric acid was evaporated to dryness and siZica (a) removed in the usual manner. The filtrate was evaporated to dryness and a small additional quantity of silica (b) separated From this filtrate iron and ABSTRACTS OF CHEMICAL PAPERS aluminium were precipitated as basic acetates and collected.This pre- cipitate was dissolved in hydrochloric acid a few drops of nitric acid were added and after cooling the bases were reprecipitated by ammonia washed dried ignited and weighed. This precipitate was dissolved in hydrochloric acid and a third portion of silica (c) obtained by filtra-tion. W. F. (‘New Mineral” from Buwnah.” By D. WALDIE. THEauthor publishes the results of an analysis of a “mineral,’’ the physical characters of which he failed to notice and the locality of whose occurrence in Burmah he did not determine. The percentage numbers are-Copper .............. 17.000 Silver................ 0.096 Iron ............... 36.470 Antimony ............ 1.150 Arsenic .............. 32.700 Sulphur.............. 1.360 Earthy matter ........ 0.560 89.336 The deficiency of over ten and a half per cent. is supposed to ariee from loss of arsenic during the analysis. The silver is equal to 31i ounces troy to the ton. A second sample subsequently received from the same source has a laminated structure and uneven fracture is somewhat cellular and of a steel-grey colour with a purplish tint and metallic lustre; it is rather redder than mispickel. Minute specks of brownish-green matter were occasionally seen particularly near the lamellae. It gives no streak on paper a dark-grey one on porcelain has a hardness =5.5 and a sp. gr.from 7.3 to 7.4. Its composition is :-Soluble in hydrochloric acid :-Copper oxide.. .... 1.21 Iron protoxide ....1.97 Lead oxide ...... 1-89 Arsenious acid .... 1.12 7 6.19 Insofuble in hydrochloric acid Copper.. .......... 12-13 Iron.. ............ 42.12 Arsenic .......... 38.45 Antimony ........ 0-54 Earthy matter.. .... 0.12 -93-36 99.55 * Chemical News xxiii 4. PUBLISHED IN BRITISH AND FOREIGN JOURNALS. 115 The constituents approximate to two equivalents of arsenic six of iron and one of copper. The author named this substance O'Rileyife. W. F. Supposed Native Copper. By H. BOWMAN." THE specimen was found in a cargo of copper pyrites from the Tharsis mines in Spain. It weighed 215 lbs. and has a sp. gr. of 8.4. The colour varies in different parts from copper-red to almost white with a hackly fracture. The interior is full of cavities above shot size ; the outer surface has no adherent matrix.Its composition is :-Copper............ 84.80 Iron .............. 5.54 Zinc.. ............ trace Nickel ........... 0.28 Cobalt ............ 0.14 Antimony ........ 0.50 Arsenic .......... 7.10 Sulphur .......... 0.75 Oxygen .......... 0.41 -99.50 In three samples the percentages of iron were 4.8,5.4 and 8.1. Zircons.-A. H. Chnrcht examined some rounded pebbles each weighing about 2 grs. which came from Mudgee New South Wales and identified them as zircons. The specific gravity of the Mudgee stones was 4.704. They resembled the stones obtained from Expailly in Anvergne. w. v. #ahn/ite from Nine Hill Frunklin Furmce New Jersey. By G.J. BRUSH.$ THEMine Hill mineral differs from the gahnite of other localities in the frequent occurrence of the cubic plane. These planes are often the largest giving the crystals the form of cubes with truncated dodecahedra1 edges and only small octohedral planes. There are also minute planes of the trapezohedron 2-2 truncating the edges of the dodecahedron ; others of the trigonal-trisoctahedron 3 j and sometimes * Chemical News xxiii 19. t Chem. News,xfi 78. $ Amer. Journnl of Scienoe [S] i 28. ABSTRACTS OP CHEMICAL PAPERS. two planes betwem the cubie and octahedral which qpem Go belong to the forms 4-4and 8-8. These surfaces rounded and feeblylustrous blend in a curved surface and do not admit of accurate measurement. The inclinations on a cubic plane are for 4-4 160" 30'; for 8-8 170" 30'.The crystals vary in diameter from 4th to 16 inch are blackish green their fragments being olive-green and have a hard-ness = 7.5 and a specific gravity = 4.89 -4-91. Two analyses gave as a mean result :-Oxygen ratios. Alumina ............ 49.78 28'20) 25.77 Ferric oxide ........ 8.58 2-57 Zhc oxide.. ........ 39.63 Manganous oxide .... 1.13 Magnesia .......... 0.13 0.05 I Silica .............. 0.57 99.81 This gives the ratio of oxygen of R and R ae 1 3.17. By assum- ing 1.56 per cent. of the ferric oxide to be present as the lower oxide the ratio is exactly 1to 3. This variety of grthnite is richer in zinc than any heretofore examined. It occum in association with black mica apatite calcite and a brownish variety of chrysolite which con-tains zinc.w.P. Qrl the Mineral Constitueds of Neteorites. By N. STORY-MASKELYNE.* THE Bredemback meteorite.-This metmemite fbund at Breitenbach in Bohemia bears B great resemblance to the siderolite of Rittersgriin in Saxony. It is a spongy metallic mass the hollows of the iron being filled by a mixture of crystalline minerals. These are a bronzite with the formula Mg$ Fe+Si03 orthorhombic in its crystalline form. The crystallography of this minepal was investigated by von Lang and has been published in Pogg. Ann. cxxxix 315. Secondly a mineral composed of silica having the specific gravity Of quartz after fusion and crystallised in the orthorhambic system. The elements of the orgstal are-n :b :c = 1.7437 :1 3.3120 ad the anglm-100 101 = 27" 46' 100 110 =60" 10' 110 101= 63" 19' * Proc.Roy. Society xix 266. ORGANIC CHEMISTRY. The optic axes lie in a plane parallel to the plane 0.10 the first mean line being the normal to the plane 100. They are widely sepa- rated and present in air an apparent angle of 107". This mineral is beyond question orthorhombic and as the tridymite of von Rath is hexagonal in its symmetry the mineral of the Breitenbach siderolite will be a trimorphic form of silica. Its specific gravity was found to be 2.245 that of tridymite being 2.295 to 2.3 and that of quartz 2.65. The analysis of the mined by distillation of the silica as silicic fluoride and subsequent determination as potassium fluosilicate gave 97.43 per cent.of silica the remainder being oxide of iron and lime. A second analysis gave 99.21 per cent. silica and 0.79 residue.. The nickeliferous iron the chief constituent of this meteorite is an alloy of the formula FeloNi and contains a trace of copper. In addition to the above minerals the iron encloses occasional well developed octn- hedrons of chromite troilite and a small amount of schreibersite The XhaZka Meteorite.-Haidinger held this stone to be made up of a mineral which he termed piddingtonite and which according to von Hauer might be a compound of bisilicate and trisilicate of iron and magnesium. The latter acid silicate however no more forms a constituent of this meteorite than does the other acid silicate shepardite as Dr.Laurence Smith has shown enter into the com-position of the Bishopsville meteorite. Haidinger's view that the Shalka stone though apparently made up of two silicates a grey and a mottled variety is nevertheless composed of a single mineral species varying in colour is now confirmed by analysis. It is found to be a bronzite of the formula Mg%Fe+SiOs ;in association with it are distinct crystals of chromite. Rammelsberg who has recently published the results of his examination of this meteorite in Pogg. Ann. cxlii 275 finds in it a bronzite associated with 12 per cent. of olivine. It is probable that the meteorite varies in composition in different parts and that Rammelsberg analysed that portion in which an olivinous ingredient occurred in appreciable preponderance. On treating the mottled variety with hydrochloric and sulphuric acids it was noticed that the action was in each case confined to that of a solvent. W. F.