COMPTCTNITE. 8^ 



Very small, moss-like, grouped crystals ; massive : 

 composition granular. Individuals cleavable. 



Colour lead-grey, inclining to blue. Lustre metal- 

 lic, splendent (in the interior), shining. Opake. 



Soft, sectile. Soils a little. Sp. Gr. = 8444, 

 BAUERSACHS. 



This mineral has been formerly confounded with hexa- 

 hedral Lead-glance. It is very probable that when better 

 known, it will be found to belong to the same genus. 



Before the blowpipe it shews nearly the same phenome- 

 na as hexahedral Lead-glance ; the only variety hitherto 

 known communicates a smalt blue colour to glass of borax. 

 It consists, according to Du MENIL, of 



Lead 62-89. 



Arsenic 22'47. 



Sulphur 0-47. 



Iron 2-11. 



Cobalt 0-94. 



Arsenical Pyrites 1 *44. 



The loss of 9'76 is attributed to intermixed rhombohedral 

 Lime-haloide. The contents of lead and of arsenic are 

 very nearly in the proportion of 73*34 : 26-66, correspond- 

 ing to BERZELIUS' formula Pb As. 



It has hitherto been found only in the level of St George 

 near Clausthal in the Hartz, in a vein of clay-slate and 

 brown-spar, traversing greywacke. It was first described 

 by Messrs BAUERSACHS and Du MENIL. 



COMPTONITE. 



KOUPHONE-SPAB. 



Comptonite. BREWSTER. Edin. Phil. Journ. Vol. IV. p. 

 131. BROOKE. Ibid. Vol. VI. p. 112. PHILL. p, 201. 



Prismatic. Combination observed nearly similar 

 to Fig. 25., without o. Inclination of i on i = 



VOL. III. 



