Zinc. 319 



SPECIES IV* 



Mineralized by Sulphur , by means of Iron. 

 Blende. PJeudo^galena. Black Jack. 



14. Of this there are feveral varieties, ge- 

 nerally of a lamellar or fcaly texture, and 

 frequently of a quadrangular form, refem- 

 bling galena, they all lofe much of their weight 

 when heated, and burn with a blue flame ; 

 their fpecific gravity is inferior to that of ga- 

 lena. Almoft all contain a mixture of lead 

 ore, moft of them exhale a fulphureous fmell 

 when fcraped, or at leaft when vitriolic or 

 marine acid is droped on them. 



I. VARIETY. 



Bluiflj Grey, and of a Metallic Appearance^ 

 Glanz Blende. 



15. Its form is generally cubical or rhom- 

 boidal, its texture fcaly or fteel grained ; by 

 calcination it lofes nearly 7 of its weight; 

 after calcination it is more eafily fqluble in 

 the mineral acids. 100 Parts of it afforded 

 Mr. Bergman about 52 of zinc, 8 of iron, 

 4 of copper, 26 of fulphur, 4 of water, and 

 6 of filex. 



1 6. To analyfe this ore in the moid way, 



Mr. 



