PHYSIOGRAPHY. 



Prehnite. 



117 



tallic. Infusible before the blow-pipe, alone ; with salt of phosphorus, 

 very slowly soluble, and the globule assuming a yellowish color. 



POLYSPH^RITE. 



In single rounded balls or drops, whose internal structure is 

 concentric. 



Lustre resinous. Color, liver-brown, clove-brown, yellowish- 

 brown, yellowish grey, and nearly isabella-yellow. Streak white/ 



Hardness (scale of BREITHAUPT) =^4-0. Sp. gr. = 5-89.. . 

 6-092. 



1. It is composed of oxide of lead, phosphoric acid, and alumina. 



2. It is taken occasionally from diggings in the district of Freiberg : 

 it is also found at Georgenstadter. 



POONAHLITE. 



Primary form. Right rhombic prism. M on M' = 92 20'. 



Lustre vitreous. Color white. Transparent. . . translucent. 



Hardness nearly that of Mesotype. 



1. It is found implanted upon, and traversing Apophyllite, and as- 

 sociated with Stilbite, Epistilbite and Calcareous Spar, at Poonah in the 

 East Indies. 



PRASE. (See Quartz.) 



PREHNITE. Axotomous Kouphone- Spar. 

 MOHS. 



Primary form. Right rhombic prism. M on M y = 

 99 30'. 



Secondary forms. 



Fig. 339. Fig. 340. 



