118 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



LEMHI COUNTY 



In Lemhi County pyrrhotite is a common mineral in the cobalt 

 ores of the Blackbird district intergrown with quartz and possibly 

 also as a segregation in diabase. It is all slightly nickeliferous, one 

 specimen from the Togo claim yielding upon analysis 0.8 per cent 

 nickel. 94 A specimen from the Togo claim examined by the writer 

 contained masses of clean glistening pyrrhotite up to 2 centimeters 

 in diameter in quartz. These gave a distinct reaction for nickel 

 with dimethylglyoxime. In the Indian Creek district pyrrhotite 

 occurs as a constituent of gold ores, especially in the Kittie Burton 

 mine, where it is associated with pyrite and quartz. 



OWYHEE COUNTY 



Pyrrhotite occurs in the form of coarse bronzy grains intergrown 

 with galena and sphalerite in heavy masses of auriferous sulphides 

 from the gold vein of the Bergh mine 1 1 miles north of De Lamar. 



SHOSHONE COUNTY 



In the Coeur d' Alene district massive pyrrhotite was abundantly 

 present in the deep level ores of the Standard-Mammoth and Green- 

 hill- Cleveland ore shoots, where it was intergrown with pyrite, siderite 

 sphalerite, and magnetite and galena. It occurred similarly though 

 less abundantly in the Tiger Poorman mine. Masses of granular 

 pyrrhotite up to several inches in diameter occur in the rich galena 

 ores of the Hercules mine and it is present in the Helena-Frisco and 

 Morning mines. East of Kellogg pyrrhotite is very abundant in 

 heavy masses with pyrite and chalcopyrite in a quartz ankerite 

 gangue in many commercially valueless veins in the Prichard forma- 

 tion as the Teddy, Lucky Boy, Wisconsin, Enterprise, Evolution, 

 and other claims. It occurs abundantly in many of the mines on 

 Pine Creek intergrown with other sulphiaes. In ore from the Inter- 

 national mine it occurs in quartz intergrown with contemporaneous 

 pyrite, galena, and sphalerite, all of which replace the quartz along 

 fractures. Specimens from the Nabob mine show large masses of 

 pyrrhotite replacing quartz with a very little galena and chalcopyrite. 

 An interesting specimen from the Sherman mine contains large 

 vitreous masses of pyrrhotite with conchoidal fracture in quartz with, 

 ankerite and prochlorite. The pyrrhotite forms films penetrating 

 the coarse ankerite crystals along cleavage planes. Like pyrite 

 pyrrhotite sometimes occurs disseminated in the Prichard formation 

 remote from mineral veins. Pyrrhotite is also a constituent of copper 

 ores in the Monitor, Black Prince, and other mines in the St. Joe 

 Basin. 



«*J. B. Umpleby. U. S. Qeol. Survey Bull. 528, p. 163, 1913. 



