94 



PHYSIOGRAPHY. 



Calamine. 



2. It occurs at Real de Minas in Mexico. 



CALAMINE. Rhombohedral Zinc-Baryte 

 MOHS. 



Primary form. Rhomboid. P on P' =107 40'. 

 Secondary forms. 



Fig. 80. 



Fig. 81. Fig. 82. 



Siberia. 



gong 137 8 / 



Rezbanya. 



monm 113 31'. 



Cleavage^ parallel with the primary form perfect, ofter 

 curved. Fracture uneven, imperfectly conchoidal. Sur- 

 face of the primary faces generally curved, and often rough, 



Lustre vitreous, inclining to pearly. Color white, though 

 seldom pure : generally grey, green, or brown. Streak 

 white. Semi-transparent . . . translucent. 



Brittle. Hardness =5-0. Sp. gr.=4-442. 



Compound Varieties. Reniform, botryoidal, stalactitic, 

 and other imitative shapes ; surface generally rough, com- 

 position columnar. Massive : composition granular, some- 

 times impalpable ; strongly coherent. By decomposition, 

 it becomes friable and earthy. Crystalline coats and pseu- 

 domorphoses formed after crystals of Calcareous Spar. 



