MINERALOGICAL CHEMISTRY. Mineralogical Chemistry. Mineralogical and Crystallographical Notices (continued). By A. TON LASAULX (Jahrb. f. Min. 1876 353-368).-Aerinite a new mineral is characterised by its intense and brilliant colour vary- ing from dark-blue to light sky-blue. It possesses a dense indistinctly fibrous foliated structure being at the same time of a thoroughly earthy nature a crystalline structure being scarcely discernible. A thin section still exhibited a deep blue colour and was distinctly pleochromatic the colours varying from dark sky-blue light-blue to yellowish-blue. In polarised light the section appeared almost uni- formly of a dark-green colour thus differing from lazurite which still retains its blue colour in polarised light.The crystal-system is probably either rhombic or clinoaxial. Hardness 3 to 4; some parts can be scratched with the finger-nail others only with a knife. Streak-light bluish-grey. Binds together before the blowpipe forming eventually a grey blistered slag containing here and there small metallic magnetic grains proving the presence of iron. Acids attack the mineral easily in the cold quickly removing the blue colour and causing a depositim of powdery silica. From these reactions it is evident that the mineral is neither vivianite crocydolite nor lazulite. A portion of the mineral was fused with sodium carbonate and analysed when its percentage composition was ascertained to be as follows :-Si&. Al,OS. Fe,O:;&FeO. Mn203. CaO. MgO. H,O. 48.528 7.551 32.785 1.167 3.586 0.900 6.158 = 100,675 A previous spectroscopic examination had proved the absence of alkalis.It is evident that the mineral must be a hydrated ferroso- ferric silicate (ferric oxide predominating) belonging either to the same class of minerals as gillingite or to the chloropals. Specific gravity 3.0185. Prom a microscopical examination the author observed that aerinite is the cement or binding material of a great mass of what are apparently cleavage- pieces of quartz olivine felspar and augite which are regularly embedded in it sometimes in clumps and round masses and occasionally separated by broad zones of the blue mineral. The quartz occupies only a secondary position exhibiting at times however a hexagonal section and containing very large fluid enclo- sures which are moveable.The felspar is often observed slightly decomposed into serpentine. From the manner in which the particles of olivine occur in agrinite the author considers it highly probable that the latter is a secondary product from the former as portions of olivine which are near one another but separated by agrinite possess uniform polarisation thus showing that they all probably belonged to ABSTRACTS OF CHEMICAL PAPERS. the same individual originally. Magnetite also occurs in the mass with apatite which is often intergrown with quartz and plagioclase. Hollow spaces are observed not only in the aerinite but also in the embedded minerals sometimes containing a finely fibrous radiating zeolitic mineral.This zeolitic mineral appears to exert some influence upon the colour of the aerinite as the latter has a leek-green colour at the points of contact with it. Pilinite a new mineral occurs in hollows in the granite of Striegau as a felt-like formation of extraordinarily fine colourless or white flexible needles. The straight needles never exceed 0.01 mm. in breadth and have a tabular appearance owing to the predominance of two faces in the zone of prismatic development indications of other faces in this zone being very rare. Indistinct sections appeared to be elongated rhombs. A very distinct cleavage was observed at right angles to the direction of prismatic development no doubt being a basal cleavage as all the larger prisms are closed by this cleavage face ; in addition to the basal cleavage there is also a less complete prismatic cleavage.Examined in polarised light the mineral proved to be double refractive the principal directions of vibration being parallel to and at right angles to the vertical axis or coincident with the cleavage directions. Total darkness was observed when the edges of a cleavage plane (a long prismatic edge and a short basal edge) are parallel with the "chief section " of one of the crossed Nicol's prisms. Extremely small rhombic sections were obtained and measured (approximately) and found to have angles of 120" and 60" and from the other optical properties of the mineral von Lasaulx concludes that it crystallises in the rhombic system. It melts very easily in the flame of a Bunsen lamp with intumescence becoming eventually a transparent and nearly coloarless glass.In the matrix it gives off water. An analysis showed it to have the following composition :-Si02. A1203.Fe203. CaO. Li20. Mg0,Na20,K20. H20. -d -. v / 55.70 18.64 19.51 1-18 traces. 4*97=100.00 Specific gravity at 15" C = 2.263. From the analysis the formula 2CaO.A1,0,.5LiO2 + 2H,O is obtained which does not agree with the formula of any known zeolite unless it is supposed that the sodium oxide of analcime is replaced by calcium oxide when it would nearly agree wit,h the formula for that mineral but against this is interposed the crystallographic system of the new mineral. The author prefers to give it a distinct name as it does not agree with any known mineral species.The genesis of pilinite stands in direct connection with the occurrence of calcite in the hollows of the Striegau granite. Note on Ardennite.-A small brownish-yellow transparent crystal of this mineral was characterised by the predominance of the macrodome Po0 ,which was easily measured and the angle found to be 112" 15' thus agreeing very closely with the angle calculated by vom Rath viz. 112.12". The angle of-the prism was ascertained by measuring over the marcropinacoid mPm and found to be 130" 20' the angIe calculated by vom Rath being 130' 0'. The faces of a brachydome which could not be measured were observed on one crystal whilst MINERALOGICAL CHEMISTRY. another crystal nearly two inches in length and three lines in breadth was strongly vertically striated on COPand mpm.At the same time the macrodome (which was partially attached to quartz) was strongly striated parallel to the combination-edges with the pyramid. The prism of this crystal was much bent and evenly broken through at right angles to the vertical axis thus adding a basal cleavage to the other three cleavage directions already described (Pogg. Ann. 149 242; Juhrb. f. &!in. 1872 930). Impressions of the striation are observed on the quartz similar to those observed with tourmaline and microscopical apatite ; from this fact it may be safely inferred that ardennite is the primary formation. Pisani stated that ardennite always contained arsenic but the author has repeated the analysis of the specimen first described by him (Jahrb.f.Min. 1874 276) and confirms his statement that it was free from arsenic. Since then an improved method of separating vanadic acid in presence of alumina discovered by Dr. Bettendorff has enabled the author thoroughly to examine this mineral andas the result of ihe analyses it appears that there are two varieties of ardennite viz. (1)arsenic-ardennite ; (2) vanadium-ardennite the first having a very pale sulphur-yellow colour and the second a colophonium-brown colour the colour becoming darker as the percentage of vanadic acid increases and lighter as the percentage of arsenic acid increases. Bettendorff separates vanadic acid from alumina by precipitating them from their solution with ammonia as vanadate of aluminium an excess of ammonia having no influence.The precipitate is then digested with ammonium phosphate on a water-bath when the yellow precipitate becomes white a double decomposition having taken place viz. aluminium phosphate remains insoluble and ammonium vanadate is in solution. Ferric oxide does not interfere with this reaction. Two analyses were made of (1) light coloured ardennite; and (2) colophonium-brown ardennite resulting as follows :-SiO,. A1,03. Fez03. MnO. CaO. MgO. CuO. V05. AS~,.H2O. -No. 1.. 2'7.50 22.76 1-15 30.61 1.83 1.38 0.1'7 053 9.33 5*13=100*39 NO.2.. 27.84 24.22 26.70 2.17 3.01 -9-20 2.76 5.01=100*91 It is found that the percentage amounts of vanadic acid and arsenic acid vary considerably showing that they replace each other vicari- ously.Some of the arsenic-ardennites appear to have a dark colour but it is owing to an outward film of earthy pyrolusite which is easily removed by hydrochloric acid. The primary ardennite is undoubtedly vanadium-ardennite as it is always perfectly clear and transparent whilst the lighter arsenic-ardennite is completely opaque and appears rather porous thus favouring the assumption that it is a secondary product of the decomposition of vanadium-ardennite C. A. R. Analysis of Chrysocolla and Copper-pitchblende. Bp HUTCHINGS (Chern. News.,xxxiv l4l).-The minerals are from Mexico and are imported into England in large quantities for copper smelting. The chrysocolla bas a light bluish-green colour ; hard-ness 4.0.The copper-pitchblende is dark brown almost black; ABSTRACTS OF CHEMICAL PAPERS. hardness 6.0. 'It contains large quantities of gypsum intermixed and here and there copper carbonates. When large lumps are broken open they orten show drusy cavities in which the chrysocolla occurs botryoidal. This botryoidal chrysocolla is always coated over with a thin layer of quartz sometimes amorphous but more frequently betiutifully crystallised in very minute crystals. The minerals were very pure and were dried at 95" for some hours previous to analysis :-Chrysocoua. Copper-pitchblende. Silica soluble in Na&O,. . 62.42 20.63 Silica insoluble in Na2CQ3. 3.83 7.35 Copper oxide .......... 25.69 28-59 Lead oxide ............ 0.12 0.41 Ferric oxide ............0.26 10.94 Alumina .............. I 0.15 Manganous oxide. ....... trace 17.53 Oxygen ................ -3.60 } Cobalt oxide. ........... trace 0-35 Zinc oxide.. ............ 0.34 1-54 Lime .................. 0.74 0.92 Magnesia .............. 1.06 Water ................ 6.13 8.30 100.59 100.31 D. B. A Lithia-bearing Variety of Biotite. By G. W. HAWES (A.m. J. of Xci. [3] xi. 431).-This mineral is from felspar quarries in the large granite veins near Portland and Middlet'own in Connecticut. It is black and lustrous but in thin plates transparent brown anti uni- axial. Specific gravity 2.96. Results of analysis :-Silica 35.61 ; alumina 20.03 ; ferric oxide 0.13 ; ferrous oxide 21.85 ; manganous oxide 1.19 ; magnesia 5.23 ; potash 9.69 ; soda 0.52 ; lithia 0.93 ; titanic acid 1.46 ; fluorine 0.76 ; water 1.87 with a trace of chlorine.The ratio of R €k Si is 1 1 2 and thus the analvsis shows that this mica is an iron biotite in which lithia replaces par of the potash. R. R. Note on a New Cornish Mineral. By FREPERICK FIELD (Chem. News xxxiv 147).-This mineral has the formula 3FeO.P2O,. 4H,O ; it is green transparent and crystallises in rhombs ; dissolves in hydrochloric acid and loses water and turns black when heated per se. Hardness 3.5. W. R. A Sulphantimonide of Lead found at Arnsberg Westphalia. By F. PISANI(Compt. rend. xxxiii 747-749).-The mineral examined by the author was of a steel-grey colour and carious struc- ture with cavities filled with crystals.Hardness 2.5 ; density 5.73. Examination and analysis showed itl to be a true crystallised hetero- morphite. R. R. ORGAN10 CHEMISTRY. (Compt. rend., Origin of Crystalline Rocks. By A. M. L~VY lxxxiii 749-752) .-The results of a microscopic examinat'ion-which the paper describes-of certain petrosiliceous rocks invalidate in the author's opinion the theory which regards crystalline rocks as formed from vitreous rocks by a process of devitrification. R.R. Experiments and Observations on Vitreous Rocks. By MEUNIEEK STAN. (Conzpt. rend. lxxxiii 616-619).-As each group of vitreous rocks resembles in composition a group of crj-stalline rocks they might be supposed to be simply fused crystalline rocks ; but this supposition cannot be maintained on careful examination for they are found to contain water and other volatile substances.Various facts one of which is the existence of spherulitic obsidian lead to the supposition of a true devitrification. The author experimented on small fragments of obsidian in order to discover if by application of heat they would become devitrified and found that when heated for eight days to a temperature below their fusing point some samples remained practically unaltered while in others white grains of felspar and prisms of augite were developed. These crystals were probably present before application of heat. It is probable therefore that de- vitrification does not take place in obsidian and gallinace below their point of fusion.Even in a pasty condition as shown by another series of experiments these rocks are not devitrified. Nevertheless when they were fused for 36 or 48 hours and then exposed for eight days to a temperature favourable to devitrification some particles which acted on polarised light were observed showing a commencement of crystallisation. In some cases the angles of fracture were rectan- gular or hexagonal analagous to those of felspars. On analysis their composition was found to resemble that of orthose. The conclusions at which the author has arrived are that vitreous rocks are not a pro- duct of fusion of crystalline rocks but that crystalline rocks are derived from vitreous rocks by devitrification ; that obsidian and allied rocks cannot be directly devitrified owing to the escape of gas bubbles but that this devitrification takes place after they have been fused so as to expel all volatile matter. W. R.