120 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 



KOOTENAI COUNTY 



Bo mite is found in several prospects in the vicinity of Lake Pend 

 d'Oreille, as, for example in the June Bug claim on the eastern shore 

 where the bornite occurs in a quartz vein with chalcopyrite and 

 specular hematite. 



LEMHI COUNTY 



Bornite is common in Lemhi County in the ore deposits along 

 the Continental Divide where it comonly accompanies free gold x 

 In the Copper Queen mine bornite constitutes an ore of copper 

 and is the most abundant sulphide, clean masses of the mineral 

 occurring in a quartz vein. A specimen of ore from the Halcomb 

 property, Carmen Creek district, contains a peculiar bornite which 

 on tarnished surfaces grows brown scales like those formed on mohawk- 

 ite and some chalcocite. 



SHOSHONE COUNTY 



Bornite occurred in the ore formerly worked in the Snowstorm 

 mine as minute grains disseminated in quartzite with chalcocite and 

 chalcopyrite in amount sufficient to constitute a low-grade copper 

 ore. In quartz veins which intersect this disseminated mineraliza- 

 tion masses of nearly pure bornite up to 25 kilograms (50 pounds) 

 in weight were ocasionally found. Bornite has also been reported 

 from a number of copper prospects east of Mullan. 



WASHINGTON COUNTY 



Bornite is said to occur in a number of small vein deposits in the 



vicinitv of Weiser. 



CHALCOPYRITE (83) 



Copper iron sulphide, CuS.FeS. Tetragonal, Sphenoidal. 



Chalcopyrite, commonly known as pyrites of copper, is, like 

 bornite, a double sulphide of copper and iron. It contains relatively 

 much less copper than bornite, however, the copper content of pure 

 chalcopyrite being only 34.5 per cent while bornite, when pure, 

 contains 55.5 per cent. It is consequently a lower grade ore. Al- 

 though crystals of chalcopyrite are known from a few localities, the 

 common form of the mineral in Idaho is massive or granular or as 

 disseminated grains, scattered through quartz or other gangue or 

 mixed with other sulphides. In a few localities it is mined as a 

 copper ore and it occurs commonly in many mines and prospects 

 as an accessory sulphide of no commercial value. The color of the 

 mineral on fresh fracture is golden yellow, much yellower than 

 pyrite, which it otherwise resembles. Often this mineral assumes a 

 brilliant iridescent tarnish on joints and fractures and for this reason 

 it is often called peacock copper by Idaho miners, although this 

 name belongs rightly to bornite. Like other common minerals 



i J. B. Umpleby. U. S. Qeol. Survey Bull. 528, p. 75, 1913. 



