290 PHYSIOGRAPHY. 



Zinkenite Zircon. 



In twin-crystals, and massive. The twin-crystals are 

 six-sided prisms surmounted by six-sided pyramids whose 

 faces correspond to the edges of the prism. The faces of 

 the pyramid incline to one another under angles of 165 

 30', and to the lateral faces under 103. The composi- 

 tion takes place like that of Witherite. Surface, the pris- 

 matic faces striated lengthwise. 



Cleavage not observable. Fracture uneven. Lustre 

 metallic. Color steel-grey. 



Hardness=3-5. Sp. gr. = 5'30 . . . 5-35. 



1. Heated before the blow-pipe on charcoal, it decrepitates and melts 

 very easily into small metallic globules, which are volatilized; during 

 which, the charcoal is covered with a yellowish white crust. 



2. Analysis. 

 By ROSE. 



Sulphur . . . 21-68 . . . 22-58 



Antimony . . . 43-45 . . . 44-39 



Lead . . . 34.87 . . . 31-84 



Copper - . . . 0.00 . . . 0-42 



3. It is found at Wolfsberg in the Hartz, where it occurs imbedded in 

 Quartz. 



ZIRCON. Pyramidal Zircon. Mons. 



Primary form. Octahedron with a square base. P on 

 P over the base =84 20', over a pyramidal edge =123 

 19'. 



