A glossary of mineralogy . h borax or micro-cosmic salt yields a glass coloured by iron. • Dissolves in muriatic acid (if not pre-viously ignited), and is converted into agelatinous mass. Localities. Finbo, near Fahlun, in Swe-den, in acicular, diverging prisms, of a darkbrown colour, sometimes upwards of a footlong, imbedded in Quartz; also at Ytterby,in Sweden; Skeppsholm, an island nearStockholm, in black vitreous masses dis-seminated in gneiss; Krageroe, Hitteroe,Arendal, and Fille Fjeld, in Norway; Fin-land ; Miask, in the LFral; Dresden, &c. Name. From c^Sk, straight. Brit. Mus., Case 38
A glossary of mineralogy . h borax or micro-cosmic salt yields a glass coloured by iron. • Dissolves in muriatic acid (if not pre-viously ignited), and is converted into agelatinous mass. Localities. Finbo, near Fahlun, in Swe-den, in acicular, diverging prisms, of a darkbrown colour, sometimes upwards of a footlong, imbedded in Quartz; also at Ytterby,in Sweden; Skeppsholm, an island nearStockholm, in black vitreous masses dis-seminated in gneiss; Krageroe, Hitteroe,Arendal, and Fille Fjeld, in Norway; Fin-land ; Miask, in the LFral; Dresden, &c. Name. From c^Sk, straight. Brit. Mus., Case 38. Orthoclase, Bana. Orthoklas, Brei-thaupt. Potash Felspar. Oblique: pri-mary form an oblique rhombic prism. Co- 270 ORTHOCLASE. lour white, reddish-white, flesh-red, andgreyish. Lustre vitreous, sometimes pearlyon the cleavage-faces. Semi-transparent ortranslucent. Streak greyish-white. Frac-ture conchoidal to uneven and 6. 2-5 to 2-6, increasing as the pot-ash is replaced by soda or lime. Fig. 318. Fig. 319. Comp. K Si + Al SiS = silica 64-8, alumina18-4, potash 16-8 == 100 ; but a portion of thepotash is frequently replaced by lime, soda,magnesia, &c. Analysis, from Baveno, by Ahich : Silica . 65-72 Alumina . 18-57 Potash . 14-02 Soda . 1-25 Lime . 0-34 Magnesia » . 0-10 100-00 BB fuses with great difficulty to a blis-tered, turbid glass; in borax dissolves slowly,forming a transparent glass. Not acted on by acids. Localities. — English. Cornwall, in largeopaque-white crystals, in the granite ge-nerally: in irregular crj-stalline mass, ; near the old Lizard Head, ingreen Talc; St. Michaels Mount; HuelCoates, near St. Agnes, in twin crystals,converted into Cassiterite (figs. 317, 319) —Scotch. Rubislaw, Aberdeenshire; Drumi-doon, or Drimadoon, in Arran, in claystoneporphyry (fg. 318). — Irish. Slieve Corra,Mourne Mountains, in opaque-white crystals(Jigs. 316, 317), and in twins like those^fromSt. Gotthard. — Foreign. Ekatherinenburg,in
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectmineral, bookyear1861
