FORM OF QUARTZ. 



213 



summit of the rhomboid (the primitive form of the 

 quartz ;) and ought to be represented as follows : 



The primitive form being a slightly obtuse rhom- 

 boid Fig. I. of 94° 4' and 85° 56'. (See Traite 

 de Mineralogie par lc Citoyen Hauy, Tom. 2 ; 

 p. 293. Edition in 4to.) 



Fig. 2. Fig. 1. 





rcTwN\ 





y£g. 



/PI \ 



> 



• 



• 



• 



: 





fr 



rj 



r 



■ 



■ 



:.. 



X^V"" 



[ — ^ 7 





Quartz Annulaire 



2 ~ * 

 ePeA 



r P zo 



Fig. 2. P. 



Inclination of P upon r 141° 40' 

 z upon r 141° 40' 

 P & z upon o 128° 20' 

 r upon r 120° 

 In the same group are several of this form, and one 

 Laving some of the solid angles of the prism trunca- 

 ted, forming a combination of the rhombifere of the 

 Abbe Hauy and the annulaire described in this, paper. 

 These crystals which are from J of an inch to 



