166 ECONOMIC GEOLOGY 



series of lenses in a quartz-sericite schist. The principal lens 

 is about 3 ft. wide at the surface but thickens to 14 ft. at a 

 depth of 120 ft. An un worked deposit of arsenopyrite also 

 occurs in the same state in Rockbridge County in association 

 with pyrite and cassiterite in quartz-greisen bearing tin veins. 



At Carmel, New York, arsenopyrite occurs as a banded deposit 

 in gneiss, in two zones 20 ft. wide intersecting each other at 

 an angle of 60 degrees. At Braintree, Vermont, there is a 4-ft. 



FIG. 97. Vertical section in short drift near end of upper tunnel, Great 

 Gluch mine, Mineral Ridge, Nevada. A, Alaskite; Q, quartz; Q', quartz 

 (feldspathic, much broken) ; S, shaley limestone; M , mispickel ore. Mispickel 

 occurs along a fault zone on both sides of the crushed quartz especially 

 abundant on the hanging wall side. (After J. E. Spurr, U. S. Geological 

 Survey.) 



vein of arsenopyrite traversing Ordovician limestones and 

 schists. Arsenopyrite occurs in fine crystallizations in gneiss 

 at Franconia, New Hampshire, also at Jackson and Haverill, 

 New Hampshire. 



(2) The Cordilleran district carries many gold, copper and 

 other mineral deposits that contain arsenic but in the roasting 

 and smelting of these ores the arsenic is not saved as a by-product 

 but is allowed to pass off with the furnace smoke and gases. 



(3) The Pacific coast belt has two chief representatives. 



