THE MINERALS OF IDAHO 189 



STIBICONITE (222) 



Hydrated antimony oxide, Sb 2 4 .H 2 0. Amorphous. 



Stibiconite, like cervantite, is a species of poorly established com- 

 position and is exceedingly variable, especially in water content. It 

 probably includes several distinct minerals. All of the white to 

 grayish and brown alteration products of stibnite are at present 

 designated stibiconite, although no detailed work has been done on 

 the Idaho materials. 



SHOSHONE COUNTY 



At the Stanley antimony mine above Burke lumps of stibnite are 

 often coated with crusts from 1 to 5 cm. thick, of dirty white altera- 

 tion products. Nearest the stibnite these contain a layer, usually 

 less than 1 cm. in thickness, of compact material of opaline appear- 

 ance and pale brown color and waxy luster. This grades outward 

 into chalky white material containing much more water than required 

 for the stibiconite formula. In small cavities in quartz from the 

 uppermost tunnel of the Stanley mine there occur thin coatings of a 

 yellow, brownish yellow, or green material which is soluble in hydro- 

 chloric acid. The solution reacts for antimony and iron. 



Specimens from the antimony mine near Glidden Pass are fibrous 

 or bladed pseudomorphs of dirty white oxidation products after 

 stibnite. 



Much of the vein material along the outcrop and in surface work- 

 ings of the Coeur d'Alene antimony vein on Pine Creek consists of a 

 breccia of bleached and altered slate fragments cemented by earthy 

 or chalky white, grayish, or brown hydrated antimony oxides referable 



to stibiconite. 



CUPRITE (224) 



Cuprous oxide, Cu 2 0. Isometric. 



Cuprite, or red copper ore, is known from a number of copper- 

 bearing veins in Idaho, where it has formed from the oxidation of 

 primary copper-bearing sulphides. The following localities have 

 been noted. 



CUSTER COUNTY 



In the Alder Creek (Mackay) district specimens of ore from the 

 300-foot level of the Alberta mine contain nodular bunches of cuprite 

 embedded in chrysocolla. The nodules, which are an inch or less 

 across, invariably are surrounded by a layer of tenorite about an 

 eighth of an inch thick. 92 



Specimens from the Mackay district contain some deep red crystals 

 resting on limonitc crusts on garnet rock containing disseminated 

 chalcopyrite. These were suited for measurement on the goniometer 



* 2 .T. B. Umpleby. V . S. Gcol. Survey, Prof. Paper 97, p. 52, 1917. 



