PHYSIOGRAPHY. 



Galena. 



219 



Rather sectile. Hardness =2*5. Sp. gr. = 7*568, of 

 a cleavable variety. 



Compound Varieties. Twin-crystals ; face of composi- 

 tion parallel, axis of revolution perpendicular to a face of 

 the octahedron. 



Fig. 209. 



Kapnik, Transylvania. 



Reticulated, tabular, and some other imitative shapes, 

 the individuals of which are often still observable. Massive : 

 composition granular, of various sizes of individuals, some- 

 times impalpable. In this case the color becomes pale, or 

 whitish lead-grey, the fracture even, or flat conchoidal, and 

 the streak shining. The granular particles of composition 

 sometimes become elongated, or compressed in one direc- 

 tion, and then approach to lamellar or columnar ones. 

 Pseudomorphoses of Pyromorphite. Plates, &c, 



1. Before the blow-pipe, it melts, if heated with precaution, and yields 

 after the sulphur has been driven off, globules of metallic lead. It is 

 partly soluble in nitric acid, and leaves a white residue. 



2. Analysis. 

 By THOMPSON. 



Lead 85-13 



Sulphur 13-02 



Iron 0-50 



