ORDEttX. HEXAHEDUAL COBALT-PYRITES. 455 



tabular prisms, sometimes disengaged from contact with 

 others. It occurs generally, however, in reniform or glo- 

 bular compositions, consisting of very thin columnar indi- 

 viduals ; the individuals of its granular compositions are 

 often impalpable, the fracture being uneven, flat conchoidal, 

 sometimes even. The surface of the imitative shapes is 

 rough, drusy, or granulated, and subject to tarnish ; so are 

 also the faces of fracture, which assume in tune a dark grey 

 colour. Their metallic lustre is united to a more or less 

 dark steel-grey colour, inclining to tin-white in the radiated 

 varieties, but which becomes blackish in the streak, and as- 

 sumes a slight degree of lustre. It is brittle, its hardness 

 is = 5-5, and the specific gravity of a radiated variety = 

 7 '280, of a compact variety = 7-064 ; the ktter ought per- 

 haps to be larger, on account of the numerous interstices in 

 the compound mass. 



According to JOHN, the radiated white Cobalt consists of 

 Cobalt 28-00. 



Arsenic 65 '75. 



Iron, with Manganese 6-25. 



Its mixture may be expressed by Fe As 2 4- 2 Co As 

 + 2 Co As 2 , which gives the ratio among the above men- 

 tioned metals = 26-46 : 67-46 : 6-08. 



The locali ty of the radiated variety is Schneeberg in Sax- 

 ony ; the compact ones are found at the same place, but 

 also at Annaberg, Joachimsthal, in the district of Siegen, 

 &c. The Cornish variety probably also belongs to this spe- 

 cies. It is preferred to the octahedral Cobalt-pyrites hi the 

 smalt manufactures. 



2. HEXAHEDBAL COBALT-PYKITES. 



Hexahedral Cobalt-Pyrites or Silver- White Cobalt. JAM. 

 Syst. VoL III. p. 279. Man. p. 269. Bright White 

 Cobalt. PHILL. p. 278. Glanz-Kobold. WERN. Hoffm. 

 H. B. IV. 1. S. 186. Kobaltglanz. HAUSM. I. S. 157. 

 Kobaltglanz. LEOXH. S. 297. Cobalt gris. HAUY. 

 Traite', T. IV. p. 204. TabL comp. p. 107. Traite', 

 2de Ed. T. IV. p. 225. 



