PHYSIOGRAPHY. 



Mimetene. 



47 



Fracture imperfectly conchoidal, uneven. 

 Surface horizontally streaked and uneven ; the prisms are often 

 barrel-shaped, or contracted at the ends. 



Lustre resinous. Color pale yellow, passing to brown. Semi- 

 transparent . . . translucent. 



Brittle. Hardness = 3-5 .. .4-0 ? Sp. gr. = 5-0 . . . 6*4. (7-2 

 KOBELL.) 



Compound Varieties. Globular, reniform, botryoidal, fruti- 

 cose shapes : massive, composition columnar, or granular. 

 1. Alone, on charcoal, before the blow-pipe, it melts with some diffi- 

 :ulty, and is reduced at once to a number of globules of lead, attended 

 with the copious disengagement of smoke, and the odor of arsenic. When 

 a small crystal is 1 held by the forceps in the exterior flame of the blow- 

 pipe, the part within the flame melts, and on being allowed to cool, crys- 

 tallizes like the phosphate of lead under similar circumstances. 



2. Analysis. 



The specimen analyzed from Siberia was probably impure, from the 

 presence of hydrate of iron. 



. 3. This mineral occurs in veins in various rocks, accompanied by 

 Galena, Copper Pyrites, Fluor, Quartz, &c. Capillary varieties are 

 found at St. Prix in the department of the Saone in France. In Eng- 

 land, it occurs crystallized in a copper vein in granite, in Huel Unity, 

 Cornwall ; also in the parish of Endellion, and in the lead mines of Dev- 

 onshire. The locality of Johangeorgenstadt, affords handsome crystals 

 of a yellow color ; that of Nertschinsk in Siberia, furnishes reniform 

 masses, of a brownish red color. 



4. As yet, there does not appear to be sufficient ground for distin- 

 guishing the Mimetene from Pyromorphite. 



