H6 earths, siliceous. 42. Gemmi. 



doub:e refraction : is infufible by the blowpipe : fpecific 

 gravity from 3,698. to 3,761. contains alumina 71,5. ftlica 

 18,0. lime 6,0. oxyde of iron 1,5. - Klaprcth. 



C^ryW/V^wj HardiOl, pellucid, lightlfh, of a green colour which va- 

 ■•'':'-' * '• niflies in a ilrong heat, fufible by the blowpipe and 

 fparkling when melted, of a conchoidal texture. 

 'Borax lapidofus. ISyzt. nat, xii. 3. p, 94. n. 2. b. 

 Gemma pellucidiffima. Wall.fyjL i. /. 243. ».6. 

 Chryfolithus* Baum. miner, l . />. 234, 

 Chryfolite. Kirnvan. \.p, 262, Thcmf-'n chsm. Z- P' S9^' 

 Chryfolith. Schmeijfer miner. \i p']i- 



Found in Brajil, Ceylon, Siberia, Iranfylvania, and Bohemia, in 

 angular fragments, grains, and cryltallized : colour yellow- 

 ifh-green mixed with brown, or verging to olive-green: 

 furface of a fine fplintery or fjaly appearance, but fach of the 

 cryftals as have not been injured by friftion have their 

 broadeft fides longitudinally ilriate; but where the furface 

 has not fuffered by attrition, it has a confiderable luftre: 

 the regular fhape of its cryftals is a 6-fided flattened prifm, 

 terminated in 6-fided pyramids, and difl-'ers from rock cryflal 

 in having the pyramids more obtufe : fpecific gravity from 

 3,265. to 3,450. contains magr.efia 41,5. filica 38,5, oxyde 

 of iron 19,0. Klaproth. 



Smaragdus. Hard, pellucid, lightifb, grafs-green, when heated to 



120 of Wedge wood becomes blue, but recovers its 

 green colour when cold, melting before the blowpipe, 

 of a conchoidal texture. 



Borax lapidofus. SyjL nat, xii. 3./'. 95. n, 2. d. 



Gemma pellucidiffima. Wall. Jyfh 1. />. 241. n. 5. 

 ~ . Emerald. Kirixjan \. p. 247. Thomfon chem. ^. p. 556. 



Emerald, ^chmeiffer mineral, i. p. 67. 



Found in the mountains of Egspt and Ethiopia, in Peru, RuJJioi 

 and the confines of Perfta: colour from the perfefct 10 the 

 pale grafs green : cryflals hexagonal prifms, either perfect or 

 truncate on the angles and edges, terminating in truiicatcd 

 pyramids : texiure foliated : fratlure conchoidal : becomes 

 eleftric by fritlion bur not by heat : caufes a double refrac- 

 tion : melts into an opake. coloured maL at 1 56° of Wedge- 

 wood : fpecific gravity from 2,050. to 2,775.- contains filica 

 64,60. alumina 14,00. glucina i 3,00. oxyde of chromi^im 

 3,50. lime 2,56. moiflure or other volatile in^red;ent 2,00. 

 y^auquelin. 



Soranus, Hard, pdlucid, fomewhat ponderous, foliated, of an 

 hyacinth colour which is pLrnianent in a moderate 

 heat, eafily melting in a Itroii^ heat into an opaKc 

 fpumid mafs. 



