PHYSIOGRAPHY. 135 



Cobalt-Bloom. 



Cleavage, parallel to P perfect : that parallel with M 

 and T scarcely visible. Surface, P and T streaked ver- 

 tically. 



Lustre upon P pearly, particularly if produced by cleav- 

 age. The rest of the faces possess adamantine lustre in- 

 clining to vitreous. 



Color, crimson-red, cochineal-red, peach blossom-red, 

 sometimes pearl-grey or greenish grey. The red tints of 

 the former, by transmitted light, incline much more to blue 

 if seen in a direction perpendicular to P. Streak corres- 

 ponding to the color, though a little paler. If the mineral 

 be crushed into powder in a dry state, this powder pos- 

 sesses a deep lavender-blue tinge, which is not the case if 

 the powder be comminuted in water. Transparent to trans- 

 lucent on the edges. Crystals are least transparent in a di- 

 rection perpendicular to P. 



Sectile ; thin lamina? are flexible in one direction. Hard- 

 ness:^ '5 ... 2-0; the lowest degrees are upon P. Sp.gr. 

 =2*948, a red crystallized variety from Schneeberg. 



Compound Varieties. Implanted globular and reniform 

 shapes ; surface drusy ; composition more or less perfectly 

 columnar of various sizes of individuals, faces of composi- 

 tion either smooth or rough. Massive, composition colum- 

 nar, often stellularly divergent, and aggregated in a second 

 granular composition, faces of composition rough. Some- 

 times in a state of powder,- as a coating upon other mine- 

 rals. 



1. Alone, before the blow-pipe, it assumes a darker hue. Upon char- 

 coal, it emits copious arsenical fumes, and melts in the inner flame, into 

 a bead of arseniuret of cobalt. With borax and other fluxes, it yields a 

 fine blue colored salt. 



