/ 



148 



Outlines of the Mineralogy and Geology 



CLASS I.— ORDER II. 



SPECIES h—qUARTZ. 



Subspecies I, — Common Quartz. • 



m 



^ 



Common Quartz, Cleaveland^ p^ 210. Jameson^ vol. i. p. 152. Quartz, Kir 



I 



wan^ vol. I. p. 242. Aikin, p. 192, 



-#^ 



External Characters. 

 Its colours are white, orange, black and grey. Of white 



occurs greyish white, and yellowish white ; of orange, it occurs 



reddish orange ; of black, greyish black ; and of grey, greenish 

 grey and blackish grey, 



J 



Its lustre alternates from shining to glistening and glimmeringj, 

 and is vitreous and resinous. 



It is transparent, or translucent, or opaque. 

 It is amorphous and crystallized, 



i. In six-sided prisms, acuminated at one or both extremities 

 by six planes. 



( 



S. In simple six-sided pyramids. The edges and angles of 

 the prisms are variously bevilled, and their sides are sometimes 

 transversely striated, but the faces of the pyramids are smooth 

 and highly polished. They occur single or aggregated, and 

 sometimes embedded twin crystals are united longitudinally. 



The crystals are small and very small, and in the latter case, 

 they frequently invest other minerals, or line cavities, rendering 



tbem drusv. 



T 



It is very hard. 



The fracture is from coarse to fine splintery and imperfectly 

 iat couchoidal. 



It is brittle. 



