ZINC. 409 



Varieties. There are different varieties of this mineral, depending upon the structure, as 

 the crystallized, the lamellar, the fibrous, etc. ; also depending upon the colour, as the yel- 

 low, the brown, and the black blende. 



Composition. Zinc 66.34, sulphur 33.66 [Arfwedson). There can be no doubt that this 

 mineral, when pure, is a true sulphuret of zinc, which is composed of 67 zinc and 33 sul- 

 phur, or one atom of each of the constituents. But the specimens generally contain variable 

 proportions of iron, sometimes from eight to ten per cent. Formula ZnS. 



Geological Situation. This mineral is usually associated with galena, whether it occurs 

 in primary or transition rocks. With the association of the ore of lead, it is found in the lime- 

 stones of the western part of the State. In St. Lawrence and Sullivan counties, it is often in 

 large quantities. 



Uses. Zinc blende is employed in the manufacture of sulphate of zinc, or white vitriol. 

 For this purpose, it is subjected to heat in a reverberatory furnace, or exposed to the action 

 of air and moisture ; by either of which processes, the blende attracts oxygen, and is con- 

 verted into the sulphate of zinc. This mineral is also sometimes used for obtaining metallic 

 zinc, but the reduction is more difficult than with some other ores of this metal. 



LOCALITIES. 



Columbia County. Zinc blende is found in various parts of this county, associated with 

 galena and some ores of copper. At the Ancram lead mine, the massive yellow and brown 

 varieties both occur, but the latter is the most abundant. The analysis of these varieties gave 

 the following results, viz : 



I. II. 



Sulphur, 33.56 33.20 



Zinc, 61.64 57.85 



Iron, 4.30 6.45 



Gangue, 0.50 2.50 



No. I. was compact ; No. II. foliated. 



This mineral is also found at Livingston's lead mine, and near Whiting's pond in the town 

 of Canaan, where it is also associated with galena in small veins. 



Dutchess County. As the veins of galena found in the preceding county extend into this, 

 blende is probably associated with that mineral. No very important locality, however, has 

 yet been reported. 



Herkimer County. On the farm of Judge Hurlbut, in the town of Salisbury, about half 

 way between the East and West-Canada creeks, is a small vein of zinc blende associated with 

 iron pyrites. Mr. Vanuxem states that this mineral, associated with galena, iron and copper 

 pyrites, is found near Salisbury corners. ^ 



Mm. — Part n. 52 



