J 50 GEDIEGEN ARSENIK. 



being yellowish-white and translucent and 

 doubly refractive in a high degree. Lustre 

 of fractured surfaces vitreous. {Streak grey- 

 ish. Extremely brittle. Fracture conchoi- 

 dal. H. 2 to 3. S.G. 1-92 to 199. 



Comp. Hydrated carbonate of lime and 



soda, or Na C + Ca C + 5 H = carbonate of 

 soda 35'9, carbonate of lime 33-8, water 30*3 

 = 100. 

 Analysis, by J. B. Bouss'mgault : 

 Carbonate of soda . " . 34'5 

 Carbonate of lime . , 33-6 

 Water . . . . .30-4 

 Clay 1-5 . 



100-0 



Decrepitates slightly when heated, and 

 becomes opaque from loss of water. 



BB fuses rapidly to an opaque globule, 

 (which when onceformed,is no longer fusible, 

 on account of the escape of carbonic acid,) 

 and has a strong alkaline taste. 



Eeadily soluble in nitric acid with eifer- 

 vescence. Soluble in water, to a trifling 

 extent, when reduced to powder; yielding 

 a solution which reddens turmeric paper, 

 and is precipitated by oxalic acid. 



Localities. This mineral is found abun- 

 dantly at Lagunilla, near Merida, in Mara- 

 caibo, in crystals disseminated in a bed of 

 rlay, covering Trona at the bottom of a small 

 jake. The natives call the crystals of Gay- 

 Lussite clavos or nails, in allusion to their 

 elongated forms ; and in contradistinction 

 to tlie Trona, which they term urao. It is 

 also met with at Sangerhausen in Thuringia. 



Name. The name was conferred upon it 

 by Boussingault, in honour of the French 

 chemist Gay-Lussac. 



Brit. Mus. Case 46. 



Gediegen Arsenik. See Native Arse- 



Gediegen Antimon. See Native An- 

 timony, 



Gediegen Blei. See Native Lead. 



Gediegen Eisen. See Native Iron. 



Gediegkn Gold. See Native Gold. 



Gediegen Kupfer. See Native Copper. 



Gediegen Platin. See Native Pla- 

 tinum. 



Gediegen Quecksilber. See Nativk 

 Quicksilver. 



Gediegen Spiessglanz. See Native 

 Antimony. 



Gediegen Silber. See Native Silver. 



Gediegen Silvan, Werner. See Native 

 Tellurium. 



Gediegen Tellur, Hausmann. See 

 Native Tellurium. 



GEKROSSTEIN. 



Gediegen Wismuth. See Native Bis- 

 muth. 



Gedrite. a variety of Hornblende re- 

 sembling Anthophyllite. It is fibrous and 

 somewhat laminar. Colour violet-brown, 

 with a semi-metallic lustre. S.G. 3-26. 



Comp. _ 8Fe, 6Si + Al, Si + H. ? 



A.nali/sis, by Dufrenoy : 



Silica 38-81 



Protoxide of iron , .45-83 



Magnesia .... 4-13 



Lime 0-67 



Alumina .... 9-31 

 Water .... 2-30 



10105 

 Locality. Valley of Heas, near Gedre' in 

 the Pyrenees ; whence the name Gedrite. 

 Brit. Mus , Case 34. 



Gehlenite, Fuchs. Pyramidal. Usually 

 occurs in rectangular four-sided prisms, 

 which are sometimes tabular, or nearly ap- 

 proach the form of the cube. The surfaces 

 of crystals commonly rough and dull. 

 Colour grey, frequently with a greenish or 

 yellowish tinge. Lustre resinous, inclining 

 to vitreous. Opaque ; fragments feebly 

 translucent at the edges. Streak white 

 to greenish white. Fracture uneven and 

 splintery. H. 5-5 to 6. S.G. 2-9 to 3-06. 



Comp. oK3 si + ii's Si, or (Ca, Mg)3 (¥e 



Al) 2Si. 



Analysis, from Fassa by Rammelsherg ; 



Silica 29-78 



Alumina .... 22-02 

 Peroxide of iron . . . 3*22 

 Protoxide of iron . . . 1-73 



Lime 37-90 



Magnesia . . . .3 88 

 Protoxide of manganese . 0-19 

 Water and loss . . . 1*28 



100-00 

 BB with difficulty fusible : with borax or 

 microcosmic salt melts slowly to a glass 

 coloured by iron. 



Completely decomposed by muriatic acid, 

 with separation of gelatinous silica. 



Localities. Principally on Mount Mon- 

 zoni, in til e Valley of Fassa in the Tyrol, in 

 crystals which are either isolated and in- 

 vested by Calc Spar, or aggregated irregu- 

 larly in' groups. It also occurs massive, 

 forrning an extremely tough, difficultly 

 frangible rock in the same locality. 



Name. In honour of the chemist Gehlen. 



Brit. Mus., Case 36. 



Gekrosstein. A contorted variety of 



