ORDER ir. DI-PRISMATIC LEAD-BAKYTE. 131 



The individuals in Fig. 38. Bleiberg, Ca- 

 rinthia. 



5. Pr. P. | Pr + & (?r + oo) 5 . (Pr + oo) 3 . 

 Pr -f OD. Fig. 31. Johanngeorgenstadt. 



6. P GD. P 1. Pr. P. (Pr) 5 . fPr + 2. 

 Pr+1. (Pr) 5 . P + oo. (Pr-h oo) 3 . (Pr+ o>) 5 . 

 f r -f QD. Pr + QD. Fig. 169. Leadhills.* 



Cleavage. Pr and (Pr + oo) 5 often perfect, gene- 

 rally interrupted by conchoidal fracture. Traces 

 of Pr + OD and (Pr -f- oo) 3 . Fracture conchoi- 

 dal. Surface, P sometimes streaked parallel to 

 the edges of combination with (?r -J- x) 5 or 

 with Pr ; Pr + cc almost always streaked, ver- 

 tically and at the same time also horizontally, 

 the latter however less deeply. 



Lustre adamantine passing into resinous. The 

 former is often metallic, if the colours be dark. 

 Very thin crystals, and columnar compositions of 

 them often possess pearly lustre. Colour white 

 prevalent, passing into yellowish-grey, ash-grey, 

 and smoke-grey, or even into greyish-black. 

 Sometimes tinged green or blue by several spe- 

 cies of the order Malachite. Streak white. 

 Transparent ... translucent 



Rather brittle. Hardness = 3-0... 3-5. Sp. Gr. 

 = 6-465 of a white translucent variety. 



Compound Varieties. Twin-crystals: axis of 



* A crystal of this form is preserved in the collection of Mr 

 ALLAN. H. 



