Zinc. 3 T 3 



Mineralized. 



3. All the ores of zinc tinge plates of cop- 

 per when ftratified with them and charcoal, 

 only the fulphureous require previous torre- 

 fadtion. 



SPECIES II. 



Mineralized by the aerial Acid. 



Cakiform Ores. 

 Of thefe there are 4 Varieties. 



I. VARIETY. 



Pure Calx of Zin'c> Vitreous Zinc Ore, Zinc 

 Spar. 



4. Of a whitiih, grey, bluifh grey or yel- 

 lowifh colour, and of a hardnefs. generally 

 fufficient to ftrike fire with Heel ; in its frac- 

 ture it refembles quartz, amorphous, ftalac- 

 titical or cryftalized in groups, and weighty; 

 by calcination it lofes y of its weight, with- 

 out emitting a fulphureous or arfenical fmell, 

 and is infufible in the ftrongeft heat either 

 fmgly or with mineral alkali, but eafily 

 fufible with borax or microcofmic fait. In 

 the mineral acids it is foluble with effer- 

 vefcence, and with the vitriolic affords vitriol 

 pf zinc. ioo gr. of this ore contains about 



