EARTHS. SILICEOUS. 55. Qiiartzisili. 167 



Found in vafious part-s of England and Saxt/an^y in Snjailzerlani^ 

 Hun^aryy Silejia^ Bohemia, zr\d Saxony ; more commonly pcl- 

 l-acid than opake: colour moflly white, fomctimes pa!c red, 

 yellowiili or yeHdwifh-rcd^ the cryftals generally in g-raitis, 

 fometimcs rekmblins; a kidticy or a gem. 



Pjev^ada- Of a conctioulai texture, in a dauhie 6iA(kd pyramid, not 

 *««• ftriatc, 



i^ With the pyramid pcr&th 



Nitrum cryiiallus, »Sj'j/, ?w/. xii, 3, /.S-^. k* 2, c 

 Sinverby Brit^ min. I. tab. 41, 42. 

 Gmel.fiji. nat. j. />. 445. txih, \. f.^:. 



2, With the margins of th-e common bafe truDcate* 

 GmeL/yft. not, 3. ^. 445. /i^^. \»/*l, 



3; Reguhr, 



Nitrum tryft alius, Syih nai. xii. 3. ^. 84. ff. 2, d; 



bi With all the faces unequal, 



Scrn^irJ^fofs. \.f. 25. tab, 2./*. 13, 



c. With the coEimou bafe oblique. 



3, Pellutid. Dott, muf. tab, 304, Iris. 

 Pellucid with opaice particles included. 



4, OpaTc«, 



Found near BrifroJ and Buxton ^ In Convwall^ Deroyjhir-g, and 

 Northumberland^ and various parts of Europe: colour irioftly 

 white, fometimes reddifh or blackifh ; rarely hollow within : 

 the cryftals fometime-3 detached, fometimes <;luliered and ad- 

 hering together in various forms- 



Cr^ittdlus* White, pellvicid^ of a conchoidal texture, in a 6-rided 

 tranfverfely ftriate prifm. 

 Nitrum lapidofum. Sytt. not. xii. 3« p, 84, n. 2. 

 Cr\ftallus montana. Wall. fyst. I. /, 217. 52,9- 

 Sckeuchx, it. 243. /. 6, Wolf, H&fs. t. \,f. 1 . 4. 6, 

 Qefn. fig. iS.yi I, 2. Rumpb, muf. t. 52. y. 5. 3. 41 

 Rock cryrtal. Kinvan 1 . ^. 241. SchmeifJ^r min^ «. ^.. 89. 

 Rock or mountain cry Hal, Jameifon min. i. ^.143. 



1. With the prifm obliquely trunciate. 

 Born^ ind.fofs. 2. /». 89. tab. I. /l 4, 



2. With the prifms terminating at one end in a 3-fided pyramid. 

 Borx. ind.fofi, z. p. 89 Karft»LeJk*m.in^ I, p, 102. 



3. With ihe prifms terminating at oiie ciid in a 6.fided pyramid. 



not ftriate. 

 Wall, fy^t. min, I* p, 21 y^ «. 9. a. 



au The pj'ramid common to the two prifms* 



