58 NEW YORK STATE MUSEUM 



of the forms. Massive occurrences are common. Chalcopyrite 

 has a bright metallic luster; the color is a brass-yellow, often 

 tarnishing to colors resembling bornite. 



It is widely distributed in veins and vugs in gneiss, crystalline 

 schists and other metamorphic rocks and was probably formed 



Fig. 166 Fig. 167 



Chalcopyrite 



in much the same way as pyrite, with which it is frequently 

 associated. Chalcopyrite is mined in Sweden, Spain, Sudbury 

 Can., Montana and Utah. Handsome specimens associated with 

 quartz have been found in New York at Ellenville, Ulster co. 

 Chalcopyrite is the principal source of copper. 



Pyrite (iron pyrites) FeS 2 



Pyrite, the isometric form of iron disulfid, contains 53.4$ 

 sulfur and 46.6$ iron. 



The crystals of pyrite are exceedingly interesting, showing 

 as they do a diversity of form and a brilliancy of surface which 

 render them objects of considerable beauty. Some of the 

 forms of the pyritohedral group which are most frequently met 

 with in pyrite are shown in fig. 168-72. PI. 16 x shows the 

 striations so common in crystals of this species. Crystalline 

 masses of varied form are quite frequent, producing botryoidal, 

 globular, stalactitic and other shapes. The granular massive 

 varieties are common. Pyrite has a brilliant metallic luster; 

 its color is a pale brass-yellow somewhat lighter than that of 

 chalcopyrite. Pyrite occurs in almost every variety of rock; 

 the deposits in sedimentary rocks were probably formed by the 

 precipitation of the included ferruginous matter from a hot 

 aqueous solution in the presence of decaying vegetable and ani- 

 mal matter. 



