THE MINERALS OF IDAHO 



125 



PYRITE (85) 

 Iron disulphide, FeS 2 Isometric, pyritohedral 



Pyrite, commonly known to the miners as pyrites of iron, is the 

 most common and widely distributed metallic sulphide in Idaho, as 

 in most other areas, occurring in practically every ore deposit of 

 whatever sort and also in many regions in disseminated form in the 

 country rock. In ores it is usually a valueless and troublesome asso- 

 ciate of valuable metallic minerals, although in gold veins the pyrite 



Figs. 7-8.-7, Small pyrite crystals embedded in quartz, Croesus mine, Blaine County. 8, Pyrite. 

 dominantly pyritohedral crystals embedded in calcite from the parker mine, warm springs 

 district, Blaine County 



is sometimes notably auriferous, and is concentrated and smelted 

 for its gold content. When available in large bodies adjacent to 

 markets, pyrite is burned for the production of sulphuric acid, but 

 deposits of the mineral sufficiently large and pure for this purpose 

 have not as yet been found in Idaho in situations favorable for 

 economic exploitation. Only the more important of the known 

 occurrences in the State are mentioned below. 



