form tinstone of Durango, Mexico, and exhibit the combination Þ∞,¦Р∞. Analysis gave the following results: Together with 0.65 per cent. of clay and tin oxide. 2. Vanadinite.-Analyses are given of vanadinite from, I, Pinal Co., Arizona (brown); II, Pinal Co. (orange); III, Yavapai Co., Arizona (olive-green). 3. Cuprodescloizite, from San Luis Potosi, Mexico, occurs as a radiated incrustation 1 to 10 mm. thick, of a yellowish-brown colour and resinous lustre. Sp. gr. 6-203. Analysis gave V205. A8905. P205. PbO. CuO. ZnO. H2O. Total. 19.99 3.63 0.13 54.52 6.58 12.70 2.62 100-17 These numbers are in accord with the formula of descloizite, (PbCuZn),OH(VASP)O,, and confirm the accuracy of the former analyses of this mineral by Rammelsberg and Penfield. 4. Pseudomorphs of iron pyrites after magnetic pyrites, from Sulphur Creek, Colusa Co., California. The occurrence of iron pyrites in small, hexagonal tablets, 1 mm. in diameter, with rough basal planes and smooth prism planes, is regarded as a pseudomorph after magnetic pyrites. 5. Hessite from the West Side Mine, Tombstone, Arizona, occurs in quartz with cerargyrite and grains of gold. Sp. gr. 8.359. Analysis gave Ag. 6. Tapalpite from the Sierra de Tapalpa, Mexico. This rare mineral occurs with iron pyrites, galena, quartz, and silicates. From analyses of impure material, the formula Ag,Bi(TeS), is deduced. The sp. gr. of the pure mineral is 7.75. 7. Allanite from Statesville, North Carolina, occurs with zircon crystals. It is brown-black in colour, has a sp. gr. of 363, and gave on analysis the following results: Pyrrhoarsenite, a New Mineral from the Sjö Mine. By L. J. IGELSTRÖM (Jahrb. f. Min., 1888, i, Ref., 184-185, from Bull. soc. franç. min., 9, 218-220).-This mineral occurs with barytes, tephroite, calcite, and hausmannite in narrow veins in the Sjö Mine. Optically it resembles the berzeliite of Langban. Its hardness is 4. Analysis gave the following results: 100.15 As2O5 + Sb2O5. MnO. CaO. MgO. SiO2. H2O. Total. 58.06 17.96 18.68 3.58 1.02 0.85 The mineral is thus an antimony-bearing berzeliite rich in manganese, and having the formula (CaMnMg),(AsSb),O, (compare Abstr., 1887, 902). B. H. B. Pleochroism of Biotite. By E. COHEN (Jahrb. f. Min., 1888, i, Mem., 165-169).-In cordierite and in muscovite, it is easy to prove by heating that the pleochroic borders first described by Rosenbusch are due to organic matter. In biotite, however, this phenomenon can only be explained with difficulty, heating with a Bunsen burner giving a negative result. This fact has induced Michel-Lévy and others to conclude that the pleochroic portions of biotite are due, not to organic matter, but to a concentration of ferriferous mica molecules. In biotite of the granite-porphyries and gneisses of Urbies in Lower Alsace, such pleochroic borders are extremely abundant, and a number of sections have been examined by the author. When a thin section that has been carefully cleaned with ether is treated with dilute hydrochloric acid at a gentle heat, a period will be reached in which the biotite becomes considerably lighter in colour, although the pleochroic border presents no change. Even when the biotite is completely bleached, as long as the structure and double refraction remain, the pleochroic border will be unchanged. The latter disappears only when the section is strongly heated and then treated with dilute hydrochloric acid until the transparency is recovered. These experiments show that the pleochroic borders in biotite are due to organic matter whose decomposition requires a higher temperature than that of muscovite or of cordierite. B. H. B. Manganese-zinc-serpentine from Franklin, New Jersey. By G. A. KÖNIG (Jahrb. f. Min., 1888, Ref. 189, from Proc. Acad. Nat. Sci. Philadelphia, 1886, 355).-The material analysed was a compact, dark-brown serpentine, which in thin section exhibited a few grains of franklinite and of garnet. The analytical results were as follows: SiO2. MgO. MnO. ZnO. H2O. 41.70 29.24 6.91 3.10 14.04 Franklinite. Pyroxene. 4.15 Total. 1.05 100.16 Chrysocolla from California. By E. JANNETAZ (Jahrb. f. Min, 1888, i, Ref., 183-184, from Bull, soc. franç. min., 9, 211-213).A specimen of opal mixed with the hydrated copper silicate contained 13 per cent. of water. The mixture had the following percentage composition: SiO2. CuO. H2O. Fe,Og. CuCl. CaCO3. Total. In thin sections, the copper silicate appears in radiated fibres having the same optical character (negative) as a dioptase cut perpendicular to its axis. Chrysocolla from Chili and from Siberia exhibit similar optical characters. B. H. B. Analysis of Chiastolite. By W. MÜLLER (Jahrb. f. Min., 1888, i, Ref., 175-176).—The author gives the following analysis of 0-1447 gram of chiastolite from the Alexandovski mine at Nertschinsk :— ALO3. FeO3. Loss on ignition. 0.89 Sio 34.85 62.28 0.85 Total. 98.87 Very similar results are obtained on analysing the andalusite of Sanidinites from São Miguel. By A. OSANN (Jahrb. f. Min., 1888, i, Mem., 117–130).—The sanidiuites examined form part of the series collected in the Azores by Reiss and Hartung. Their structure is holocrystalline-granular. There is no amorphous cementing material, and no trace of porphyritic structure. Among the constituents of the rock, sanidine predominates, then follows hornblende or sometimes augite. All the rest, including mica and quartz, are subordinate. The accessory minerals are sodalite, zircon, pyrrhite, lavenite, titaniferous iron ore, and apatite. The sanidine is colourless and glassy, and on analysis gave the following results : SiO2. Al2O3 + Fe2O3. CaO. Na,O. K2O. 20.26 Total. 99.02 Sp. gr. 2.57 With regard to their geological occurrence and their mineralogical composition, the sanidinites form well-characterised rocks. At the Laacher See, in the Rhone, at Vesuvius, and at São Miguel, they always occur in the form of loose blocks, and have never been found in place. B. H. B. Copper Ores containing Tourmaline from Tamaya in Chili; Geological Occurrence of Boron Minerals. By A. v. GRODDECK (Chem. Centr., 1887, 1518-1519, from Zeit. Geol. Ges., 39, 237266). The tourmalines are of microscopic size (0·1 to 0·5, in exceptional cases 2 mm. long, 0·05 to 0.1 mm. broad). They occur in (1) copper sulphides (copper pyrites, purple copper ore, and copper glance), (2) in the oxidised copper ores at the outcrop of the lode, (3) in the lode minerals (calcite and quartz), (4) in the matrix. analysis gave Au H2O. 0.22 389 SiO2. Al2O3. B.03. FeO. CaO. MgO. Na O. K2O. 36.34 32.22 10.87 8.31 0.79 3.92 3.14 A calcite from the Murciélagos mine of an anthraconite colour proved to be mixed with copper glance and tourmaline. In round numbers, 22 per cent. of copper glance, 36 per cent. tourmaline, and 42 per cent. calcite. From the spathose, quartzose, micaceous, and chloritic matrix, and partition rocks of the lode, the following were submitted to analysis: I. A white, clear rock, consisting of 92 per cent. potash mica. (sericite), 3 per cent. calcite, and 5 per cent. of silica (opal?). II. The pure mica of the foregoing rock, which, however, still contained some purple copper ore, chlorite, and opal (?) III. A porphyritic rock, in the crystalline matrix of which quartz, orthoclase, plagioclase, and titanic iron were embedded. IV. A rock similar in structure to No. III, the felspar and matrix of which are changed into a fine-grained aggregate of quartz, sericite, and carbonate. V. A solid porphyritic rock, in the grey matrix of which plagioclase, magnetic iron ore, titanic iron, and hornblende are embedded. VI. A decomposed porphyritic rock consisting essentially of quartz and mica minerals, but also containing some tourmaline. No. III contains traces of TiO2; IV, 0.84 of copper pyrites; V, 0·59 P2O¿; VI, traces of SnO2 and P2O. Besides the rocks analysed, which may be perhaps regarded as dioritic porphyrites, gabbro was found under the Tamaya rocks, but pure diorite and syenite, which have been previously described, were absent. Tourmaline was absent from all the solid partition rocks, and they were free from boron. The mineral is limited to the lode, lode minerals, and matrix of the ore. The question of the formation of the lodes, whether by lateral secretion or by the rise of hot springs, the author leaves opens, but he considers the question of their formation from the activity of fumaroles to be excluded. A geological grouping of boron minerals is also given. J. P. L. The Basalts of Alsace. By G. LINCK (Jahrb. f. Min., 1888, i, Ref., 235-236, from Mitth. Commission geol. Landesunters. Elsass Lothringen, 7, 49-68).-In Alsace, basalt occurs only in two places-at Reichshofen in Lower Alsace, and at Reichenweier in Upper Alsace. The basalt from the former locality is a felspar-basalt (Analysis I), whilst the basalt of Reichenweier is a limburgite (Analysis II), similar to that occurring at Forst in the Palatinate. SiO2. TiO2. Al2O3. FeO + Fe2O3.CaO. MgO. KO. NagO. H2O. Total. I. 52.60 0.57 14:17 11.38 9.17 637 1.06 2.90 2:08 100:30 II. 42:30 1.51 12.74 10.60 13:01 12.74 0.94 2.65 2.54 99-03 B. H. B. Quartz Conglomerate from Witwatersrand, Transvaal. By P. HOLLAND (Chem. News, 57, 76-77).-The Witwatersrand reefs consist mainly of loose quartz conglomerate varying in colour from light yellow to dark-reddish or purplish-brown. A specimen of the dark variety consisted of waterworn quartz pebbles and angular fragments of coarse-grained quartzose sandstone of various sizes, mixed with siliceous matrix material. Scales of mica were also detected, but there was no "visible gold." The sample as received contained slightly more than 15 dwts. of gold per ton; whilst those portions of the specimen passing through a 4-inch mesh sieve (amounting to about half the original), contained about 1 oz. 3 dwts. of gold per ton, and had the following general composition: SiO2. Al2O3. FeO. TiO2. MnO. CaO. MgO. 85.72 4:27 6.18 0.12 0.03 0:01 trace K2O. Na O. 0.23 0:32 The gold is found chiefly in the matrix material. D. A. L. Chloritoïd-schist from Grossarl. By A. CATHREIN (Jahrb. f. Min, 1888, i, Ref., 242, from Tschermak's min. Mitth., 8, 331—337). --In the Grossarl valley, Salzburg, a schist occurs containing numerous dark-green groups of chloritoïd crystals in a yellowish-white groundmass. The latter consists of quartz, rutile, titanite, iron pyrites, and titaniferous iron ore. The pulverised rock was boiled in dilute sulphuric acid, all the chloritoïd and ore together with some titanite and rutile passing into solution. The soluble part (I) and the insoluble (II) gave on analysis the following results: SiO2. TiO2. Al2O3. FeO. CaO. MgO. H2O. Total. I. 25.50 1.88 38.69 27.19 0.40 0.08 6.67 100-41 II. 92.82 6.93 0.76 100.51 Calculated from I, the formula of the chloritoïd is approximately H2FeAlSiO. The composition of the rock, calculated from I and II, is 63.98 per cent. of chloritoïd, 30-16 of quartz, 403 of rutile and ore, and 1.83 of titanite. Thus the proportion of chloritoïd is greater than any chloritoïd schists known elsewhere. B. H. B. in |