288 PHYSIOGRAPHY. 



Jamesonite Johannite. 



Secondary forms. The primary, with its acute lateral 

 edges truncated. 



Cleavage, parallel with T highly perfect ; less distinct, 

 though easily observed, when the crystals are not too small, 

 parallel with M and the secondary lateral planes. Fracture 

 not observable. 



Lustre metallic. Color steel-grey. Streak unchanged. 



Sectile. Hardness =2-0 . . . 2-5. Sp. gr. = 5-564. 



Compound Varieties. Massive : composition colum- 

 nar, individuals generally very delicate ; straight and paral- 

 lel, or divergent. 



1. Before the blow-pipe, in an open tube, it yields a dense white 

 smoke of oxide of antimony, and leaves behind chiefly antimoniate of 

 lead. Upon charcoal, after the volatilization of the antimony and lead, 

 there remains behind a slag, which, with the fluxes, exhibits the reac- 

 tion of oxide of iron, containing traces of oxide of copper. 

 2. Analysis. 



By ROSE. 



Sulphur - - 22-15 - - - 22-53 



Lead - - 40-75 - - - .30-71 



Copper - - 0-13 - - - 0-19 



Iron - - 2-30 - - - 2 65 



Antimony - - 34-40 ... 34-90 



3. It occurs in masses of considerable dimensions in Cornwall ; also 

 in Hungary. 



JEFFERSONITE. (See Pyroxene.) 

 JOHANNITE. Cypririe Ur an ium- S al t. 



Primary form. Oblique rhombic prism. M on M = 

 111 ? 



Cleavage, parallel with M. 



Color grass-green, to siskin-green. Lustre vitreous. 

 Streak siskin-green. Semi-transparent. 



Hardness =2-0 ... 2-5. Sp. gr. = 3- 1 . . . 3-2. Taste 

 bitter, rather than astringent. 



