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366 SILICATES. e — l 636, 1-764. The optic axes are in a plane parallel to c, and make angles of 68° 30' with a normal to b. Colourless, white mclmmg to grey, green, brown, red, flesh-red, verdigris-green. Streak greyish-white. Brittle, h = eo. a = 2-53... 2-59. Melts with difficulty before the blowpipe into an opaque u ' 8S ' With borax forms a clear glass. Soluble with m&culty m salt of phosphorus, leaving a skeleton of silica. With solution of cobalt the melted edges become blue. Is not acted on by acids. IT 8 ^ ca 85 ’ 25) a l um ina 18-11, potash 16'64. Part ot the potash is frequently replaced by soda and lime. Analyses of the transparent colourless varieties (adularia) a from St. Gotthardt o = 2-5756, by Abich, I by Awdejew, c by Berthier, d from the Yalenciana mine in Mexico (Breithaupt’s valeneianite) by Plattner, e of flesh-coloured felspar from Lom- mtz by V. Eose, / of opalescent felspar from Dawlish (murchi- sonite) by E. Phillips Silica . Alumina Potash Soda . Lime . • ^ ish or transparent varieties in imbedded crystals showing the forms b, c, x, m, n (glassy felspar or samdine) g from Yesuvius by G. Eose, h from the Drachcn- lels, i from Mont d’Or, both by Berthier, k from Epomeo in Ischia, I from Arso in Ischia, m from the tufa of Pausilipo, all by Abich:— 1 Silica .... Alumina . . . Red oxide of iron Potash .... Soda .... Lime .... Magnesia . . . Oxide of mangan. a b e d e / 66'69 65-75 64-20 66-82 66-75 68-6 17-97 18-69 18-40 17'58 17-50 16-6 13-99 14-17 16-95 14-80 12-00 14-8 1-01 1-44 Ee 0-09 1-75 — 1-34 — — — 1-25 — 9 h i h 1 m 65-62 66'6 66-1 66'73 66-00 67-87 19-15 18-5 19'8 1736 18-64 15-72 — 0-6 — 0-81 0-83 2'41 14-74 8-0 6'9 8-27 9-12 668 40 37 4'10 3-49 386 0-60 10 — 123 1-23 3-10 — — 2-0 1'20 1-03 1-40 — — — 013 ■— j 8 r ^ s P ar n from Alabaschka, o from Sehaitansk by , an ^ Litton, p from Martersberg near Marienberg, a = PreihtL K 0n ifr r ’,? from Ereiber S b y Kersten, r from Muldc near S y Moll, g (Breithaupt’s mikroklin) by Evreinoff:—
