ORDER XII. HEMI-PRISMATIC RUBY-BLENDE. 43 



Char, of Comb. Hemi-prismatic. Inclination of 

 P oo on Pr + QD = 101 6'. 



Combination. 1. P QD. ?H-1. P+ QD. Fig. 



183. There occur many secondary faces ; the 

 whole has much the appearance of crystals of he- 

 mi-prismatic Vitriol-salt. 



Cleavage, i Pr + and f r + QD, imperfect. Frac- 



2 



ture imperfect conchoidal. Surface, deeply streak- 

 ed parallel to the edges of combination with 



* "*" , particularly P oo and P + QD, as in- 



Xi 



dicated in the figure ; the pyramids are smooth, 

 "*" rough, though even. 



Lustre intermediate between metallic and metallic 

 adamantine. Colour iron-black. Streak dark 

 cherry-red. Opake, except in thin splinters, 

 where it transmits a deep blood-red colour. 



Very sectile. Hardness = 2-0 ... 2-5. Sp. Gr. 



- 5-234. 



OBSERVATIONS. 



I 



1. The chemical composition of this species has not been 

 as yet exactly ascertained. Before the blowpipe it gives 

 results nearly agreeing with those of rhombohedral Ruby- 

 blende, but it contains only about 35 ... 40 per cent, of 

 silver, besides sulphur and antimony. The only speci- 

 men of it, in the possession of Mr VON WEISSENBACH at 

 Freiberg, is supposed to have been found in the mine call- 

 ed Xeue Hoffnung Gottes, at Braunsdorf near Freiberg in 



