280 zinc. 



Genus VIII.— ZINC. 



Zinc, Fr.; Zinco, It.; Zin k, Ger. ; Toolanagum, Tain.; P«-yuc<J.t7hln. 



This metal exists in, nature mineralized with sulphur or with 

 oxygen, and also with carbonic and sulphuric acids. The zinc of 

 commerce is principally obtained from calamine, a native oxide 

 of zinc, which contains a portion of carbonic acid. The ores 

 of zinc are generally associated with lead-ores, and are found abun- 

 dantly in various parts of England, particularly in veins in the 

 mountain limestone of Derbyshire, Durham, Cumberland, York- 

 shire, Somersetshire, and North Wales. 



SpA. SULPHURET OF ZlNC, OrBLENDE. Pl. XXXVIII. fig. 1. 



— Granat-Blende, Mohs. ; Zinc sulfure, Haiti/. — Its colours are 

 yellow, brown, and black. It occurs massive, disseminated, in 

 granular concretions, and crystalized, in many varieties of form, 

 of which the primitive is, according to Hauy, the rhomboidal 

 dodecahedron. Mr. Phillips says the varieties amount to not 

 fewer than fifty, some of which are represented on the annexed 

 plate. Fig. a, represents the primitive ; fig. b, the same with 

 the solid angles replaced by triangular planes, which, in fig. c, arc 

 increased greatly, forming the passage of the rhomboidal dodeca- 

 hedron into the regular octahedron, fig. d. Fig. e, is an octahe- 

 dron, which has received an increase of the crystaline laminae, pro- 

 gressively diminishing in size, on two opposite faces of the upper 

 pyramid, and on the other opposite faces of the lower pyramid ; 

 this crystal forms the passage of the octahedron into the tetra- 

 hedron, fig,/. Fig. g, is a regular octahedron, of which the solid 

 angles are replaced by quadrangular planes, which are increased in 

 fig. h, the cube. Fig. i, is a variety of the rhomboidal dodecahe- 

 dron ; and fig. j, a crystal bounded by twenty-four equal and simi- 

 lar triangular planes. The lustre varies from resinous to metallic, 

 and from shining or splendent to adamantine. It is translucent 

 or opaque. The structure is laminar, with six distinct cleavages. 

 It yields readily to the knife, which distinguishes it from tinstone ; 



