Page:Encyclopædia Britannica, Ninth Edition, v. 16.djvu/439

Rh MINERALOGY fracture conchoidal and splintery. C.c. : silica 49 8, lime 43 5, protoxide of manganese 2 3, protoxide of iron 2 9, water 37. Kilfiuiclieu and Torosay (Mull), Xonotla (Mexico). 601. TOBEUMORITE, 3(0a 4, H)Si 6 + 2jSF. Massive, fine granular; translucent; fracture hackly. H. 5; G. -=2 4. Pale pink. C.c.: silica 49 8, lime 37 2, water 12 9. Tobermory (Mull), Dunvegan (Skye). 602. OKENITE, CaHSLj + H. Right prismatic. ooP 122 19. Usually fine fibrous; radiating. H. -=5; G. =2 28 to 2 36. Pellucid; slightly pearly. Yellowish to bluish white. In powder easily sol. in h. acid, leaving gelatinous flakes after ignition. C.c.: 56 6 Bilica, 28 4 lime, and 17 water; an apophyllite without the fluorine. Disco Island, Faroes, and Iceland. 603. APOPHYLLITE, 8(CaSi + 2H) + KF. Pyramidal. P 120 56. P, oopoo (m), OP (o), ooP2 (r). Ilurely lamellar. Cl. o, perfect. Brittle. H. =4 5 to 5; G. =2 3to 3 4. Transparent; vitreous. On o pearly (Ichthyoph- thalmitc). Colourless, rarely pink, green, red, brown, and yellow. B.B. exfoliates, intumesces, and melts to white enamel. Sol. in h. acid, leaving silica. C.c.: silica 50 3, lime 247, water 15 9, Fig. 542. Fig. 544. potassium 4 3, fluorine 2 1. Dunvegan and Storr, Skye (fig. 544); Chapel, Fife ; Corstorphine (fig. 542) and Ratho, near Edinburgh ; Kilsyth, Bowling, Kilpatrick ; Port Rush, Ireland. In the form P (fig. 79), grass-green at Oxhaveer, Iceland (Oxhavccrite) ; Uto, Sweden; Andreasberg and Faroes (pink) ; Faroes, and Poonah in India (green). Internal structure tesselated, being built up of wedge and lenticular forms with varying refractive indices, hence exhibit ing a beautiful structure with polarized light. 604 . G YROLITE, (f Ca -I- jfi)Si + H. Lamellar, radiate, spherical, and investing. H. =3 to 4. Pearly. Bluish white to cream-coloured. Transparent, rapidly becoming opaque. C.c.: silica 53 3, lime 32 9, water 13 8. Quiraing, Lyndale, and Storr, Skye ; Loch Screden and Carsaig, Mull ; Canna ; Karartut, Niakornak, and Disco ; Faroes ; Nova Scotia. 605. ANALCIME, AlSi 3 -f NaS i + 2&. Cubic. ooQoo ; 2O2. Fracture uneven. H. - 5 5 ; G. - 2 1 to 2 &quot;28. Colourless, white, flesh-red, scar let. Vitreous; transparent. B.B. melts without frothing to a clear vesicular glass. Decomposable with gelatinization in h. acid. C.c. : 54 - 5 silica, 23 3 alumina, 14 1 soda, 8 2 water. Walls, Orkney ; Talisker, Skye; Sanda, and Hebrides generally. Trans parent at Eigg, and Elie, Fife scarlet at Bowdens, Kincardine; opaque white at Glen Farg, Salisbury Crags, and Dumbarton; Giant s Causeway, Seisser Alp in Fig. 545. Tyrol, Cyclopean Islands (fig. 545), Faroes, Iceland, and Nova Scotia. EudnopMte is a variety. Pecto- lite (sp. 598) occurs pseudomorphous after analcime, in large crystals of a, n, at Ratho, Ediuburghshire. 606. POLLUX, 3( AlSi 3 + (sf, Na)Si) + 23. Cubic. ooOoo ; 202 (fig. 546). Also massive. Gum-like externally. Brittle, with traces of cleavage. Fracture con choidal. H. -5-5 to 6-5; G. = 2 86 to 2 9. Colourless. Vitreous. Sol. in n. . ,..,, acid. C.c. : silica 44, alumina 16, oxide Fl & 546 (S P 606) of caesium 34, soda 2 5, water 2 4. Elba. The only mineral which contains caesium in quantity. 421 607. FAUJASITE, Cubic ; in octahedrons with the icositetrahedron |0|. Fracture uneven; brittle. H. = 7 ; G. -1 92. Transparent; vitreous to adamantine. White to brown. Sol. in h. acid. C.c. : 46 8 silica, 16 alumina, 4 4 lime, 4 8 soda, 28 water. Kaiserstuhl in Baden, Annerod near Giessen, Eisenach, Marburg. 608. CHABASITE (Lime-Chatasite), AlSi 3 + CaS i + 6H. Rhombohedral ; R 94 46. ^R ; - $R (r) ; - 2R ; ooP2 (a). Twins very common (generally interesting), on faces &amp;gt;P and Fig. 547. Fig. 548. PGO. Primary rhombohedron is sometimes twinned with a crystal with faces r, e, s. Cl. r perfect. H. - 4 to 4 5 ; G. - 2 to 2 2. Transparent or translucent; vitreous. Colourless, and brownish, Fig. 549. Fig. 550. yellowish, brick-, and flesh-red. Sol. in h. acid, leaving silica. C.c. : silica 47 8, alumina 20 8, lime 107, water 21 &quot;3. Lyndale (figs. 547, 548, 549), Talisker (figs. 176, 550, sometimes flesh Fig. 551. Fig. 552. colour), and Storr, Skye (figs. 547, 548); Port Glasgow and Kil- malcolm (pink and brown) ; Giant s Causeway and Magee Island (red), Faroes, Iceland, Aussig, Andreasberg (fig. 551). Haydenite in twinned rhombohedra, with p : p 95 to 97 and p : d 170 reentering (fig. 552), from Fassa and Maryland, is similar. Phacolite is chabasite in twins of |P2, o&amp;gt;P2, R, -JR at the Giant s Causeway (fig. 154). At Richmond in Victoria g 55 -rc- |R W |P2 (t), OP (c) ; polar edge, |P2 145. In this, half of the lime is replaced by soda. 609. GMELINITE (Soda-Chabasite), AlSi 3 + NaSi + 6H. Hexagonal. R 112 26 ; P 79 54. Combination P, OP, ooP