AbstractsEarth & Environmental Science

"In Wisconsin and other zinc mining districts the blende is frequently found associated with pyrite and marcasite. In the Wisconsin district, especially, the marcasite content of the mine-run ore is high being frequently equal to and in many cases greater than the sphalerite content. At time the marcasite and sphalerite together constitute as much as 25 or 30% of the min-run ore. The characteristic milling treatment of this ore is; first, hand-picking, and then over grizzlies, tromells, rougher and cleaner jigs. Owing to the fact that marcasite and sphalerite differ but slightly in specific gravity the jig concentrate obtained is a mixture of the two and varies in composition from all blende to all marcasite. This product, owing to the high iron content, is not suited for the zinc smelter, and magnetic or electro-static schemes of separation must be resorted to" – Problem of the Work, p. 1.