Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/405

Rh MINERALOGY 387 36 (fig. 288). 96. ANATASE, Ti0 2. Pyramidal ; pyramids dominant. P 136 basal, and P, both perfect ; brittle. H. = 5 5 to 6 ; G. = 3 8 to 3 93. Trans parent to opaque ; lustre adamantine to metallic. Indigo-blue, yellow, brown, rarely colourless ; streak white. B. B. infusible. Sol. in hot s. acid. C.c. : titanic acid, with a little iron and rarely tin. Cornwall and Devonshire, the Alps, Dauphine, Valais, the Urals, Minas Geraes (Brazil). 97. BROOKITE, Ti0 2. Right prismatic ; with polar edges 135 37 and 101 3 (fig. 289). Cl. macrodia- gonal. H. -=5 5 to 6 ; G. =3 86 to 4 -2. Transparent to opaque ; lustre metallic Fig. 288 (sp. 96). adamantine. Yellowish, reddish, and hair-brown; streak yellowish white to white. B. B. infusible ; with rnicrocosmic salt, a brownish yellow glass. C.c. : titanic acid, with 1 to 4 5 per cent, peroxide of iron. Snowdon and Tremadoc (Wales), Chamouni, Bourg d Oisans, Miask. Arkansitc is iron-black, and submetallic, in thick crystals from Arkansas, U. S. 98. CASSITERITE, Sn0 2. Pyramidal. P 87 7 ; Poo 67 50 (figs. 290 to 292). Crystals ooP, P; or oo P (g), P (s), oopoo(0; or with Poo (P), (fig. 290); and also ooP2 (r), and 3P3 (2), (fig- 291). Hemitropes very common, combined by a face of Poo with thechief axes 112 10 (figs. 293, 171, 172, 173) ; also fibrous ( Wood Tin), or in rounded fragments and grains (Stream Tin). Cl. pris matic along ooP, andooPoo, imperfect; brittle. H. =6 to 7; Fig. 289 (sp. 97). Fig. 290. Fig. 291. (1. = 6 8 to 7. Translucent or opaque; adamantine or resinous. White, but usually grey, yellow, red, brown, and black ; streak white, light grey, or brown. B.B. in the forceps infusible ; on Fig. 292. Fig. 293. charcoal, in the inner flame, reduced to tin. Not affected by acids. C.c. : 78 6 tin and 21 - 4 oxygen, but often mixed with peroxide of iron, or manganese, or tantalic acid. Cornwall, Bohemia, Saxony, also Silesia, Haute-Vienne in France, Greenland, Russia, North and South America, Malacca, Banca, and Queensland. Almost the only ore of tin. 99. HAUSMANNITE, 2MnO, Mn0 2. Pyramidal. P 116 59 ; Poo 98 32 (fig. 110). Twins common, and rosettes of twins (figs. 174,175). Cl. basal, perfect, less so P and Poo ; fracture uneven. H. =5 5 ; G. =47 to 4 8. Opaque; metallic lustre. Iron-black ; streak brown. B. B. infusible, but becomes brown. Sol. in h. acid, with evolution of chlorine. Powder colours s. acid red. C.c. : 31 protoxide and 69 peroxide of manganese. Ihlefeld and Ilmenau in the Harz, and Sweden. 100. BKAUNITE, MnO, Mn0 2. Tetragonal. P 108 39. Cl. P ; brittle. H. =6 to 6 &quot;5 ; G. =47 to 4 9. Metallic lustre. Colour and streak dark brownish black. C. c. : 70 manganese and 30 oxygen, generally with about 8 per cent, of silica. Ihlefeld and St Marcel. Marcelinc has violet tarnish. 101. PYROLUSITE, Mn0 3. Right prismatic ; ooP9340 ; generally radiating fibrous, orcompact earthy. Cl. ooP ; friable. H.=2to2 5; G. =4 7 to 5. Opaque; lustre silky to semi-metallic. Dark steel-grey to black ; streak black. Soils. B. B. infusible, loses oxygen and becomes brown. Sol. in h. acid, with evolution of chlorine. C.c.: manga nese 63, oxygen 37. Arndilly (Banffshire), Cornwall and Devon, Ilmenau, Ihlefeld, France, Hungary, Brazil. Used for re moving the green iron tint from glass ; hence its name and that of Savon dc verrier. Also for obtaining oxygen and chlorine. Var- vicite is a variety with 5 per cent, of water, from Warwickshire. 102. CREDNERITE, 3CuO, 2(MnO,Mn0 2 ). Oblique. H. =4 5; G = 5. Metallic. Black; streak brown. Thuringia. 103. PLATTNERITE, Pb0 2. Hexagonal. o&amp;gt;P120. Cl. indistinct ; brittle. G. =9 4. Opaque; metallic. Iron-black; streak brown. C.c.: lead 86 2, oxygen 13-8. Leadhills. 104. MINIUM, 2PbO, Pb0 2. Pulverulent. H. = 2 to 3 ; G. = 4 6. Dull. Colour bright red ; streak orange-yellow. B.B. fuses easily and reduced. Sol. in h. acid. C.c. : lead 907, oxygen 9 &quot;3. Leadhills, Weardale in York shire, Anglesea, Badenweiler, Siberia. 5. HYDROUS OXIDES. 105. SASSOLINE, B 2 3, H 2 0. Anorthic. OP : ooPoo 75 30. Scaly six-sided plates. Cl. basal. Flexible and sectile. H. =1; G.-=1 4 to 1 5. Translucent; pearly; white; taste bitter; greasy. Sol. in hot water. C.c.: boracic acid 56 45, water 43 55. Hot springs of Sasso, near Siena, Tuscany ; and with sulphur in the crater of Volcano, Lipari Islands. 106. TURGITE, 2Fe 2 3 + H 2. Massive and fibrous, also earthy. H. = 5 to 6 ; G. =3 54 to 4 68. Lustre satin-like, also dull. Colour reddish black to bright nil. Botryoidal surfaces lustrous like limonite. Opaque. C.c. : iron sesquioxide 947, water 5 &quot;3. B.B. decrepitates violently and yields water. Kerrera (Hebrides), Bogoslov.sk (Urals), and many limonite localities. Fre quently taken for limonite. 107. DiAsroiiE, A1 2 3, H 2 0. Right prismatic ; ooP12947 ; usually thin foliated. Cl. brachydiagonal, perfect ; brittle. H. =6;G. =3 3 to 3 4. Vitreous; pearly on cleavage-planes. Colourless to yellowish, greenish, or violet. B.B. infusible, decrepi tates. Insoluble. C.c. : alumina 85, water 15. Schemnitz, Broddbo, Switzerland, Naxos, Chester, Massa chusetts. Fig. 295. 108. GOTHITE, Fe 2 O 3, H 2 0. Right prismatic; ooP 94 53 ; also columnar, fibrous, or scaly. Cl. brachydiagonal, perfect ; brit tle. H. =5 to5 5; G. =3-8 to4 4. Opaque ; or fine crystals trans parent, and hyacinth-red ; lustre adamantine or silky. Colour yellow, red, or dark brown ; streak brownish yellow. 15. B. becomes magnetic, difficultly fusible. Sol. in h. acid. C.c. : peroxide of iron 90, water 10. Hoy (Orkney), Achavarasdale (Caithness), Salis bury Crags (Edinburgh), Lost- withiel, Clifton, Bristol, Przibram, America. Fig. 295 (sp. 107). Siegen, Saxony, Fig. 297. Urals, North