THE MINERALS OF IDAHO 



235 



Analysis of siderite, Hemlock claim 

 (Earl V. Shannon, analyst) 



Constituent 



Ratios 



Insoluble (quartz) 



Manganese carbonate (MnCCb). 



Iron carbonate (TeCCh) 



Magnesium carbonate (MgOCh) 

 Calcium carbonate (CaCCb) 



Total 



Although rather higher than the last in magnesia, this is also 

 definitely classifiable as siderite. 



RHODOCHROSITE (274) 

 Manganese carbonate, MnC0 3 . 



Rhombohedral. 



Manganese carbonate is much rarer in Idaho than the other 

 members of the group previously discussed. The following occur- 

 rences have been noted. Few analyses of the gangue carbonates 

 have been made, however, and, should rhodochrosite occur in some 

 color other than the usual pink it would probably fail of recognition. 



BLAINE COUNTY 



A little of a pinkish carbonate, which is probably rhodochrosite, 

 occurs as a gangue mineral in a specimen of silver ore from the Hub 

 mine on Lava Creek, 2 miles southwest of Martin in the Lava Creek 

 district. 



A specimen of silver ore in the National Museum (Cat. No. 56536, 

 U.S.N.M.) labeled " Neptune mine, Alturas County," contains 

 rhodochrosite. Alturas County no longer exists, having been divided 

 into Elmore and Blaine Counties. The exact location of the Nep- 

 tune mine has not been determined. The specimen, which is about 

 1 pound in weight, is nearly half rhodochrosite, the balance being 

 coarse white quartz which contains coarse granular sphalerite varying 

 abruptly from black to yellow in color, and some pyrite. The 

 rhodochrosite is fine granular and light pink in color. 



KOOTENAI COUNTY 



Rhodochrosite occurs in the Conjecture mine of the Lakeview 

 Silver Mining Co. south of the town of Lakeview at the southern 

 tip of Lake Pend Orielle. The specimens were collected by Edward 

 Sampson of the United States Geological Survey from the dump, 

 the mine being flooded at the time of his visit in 1920. The ore of 

 this mine consists principally of galena, some pyrite, and dark- 

 colored sphalerite, and a little tetrahedrite. In places in the same 

 vein system stibnite is found and in one place, quartz stringers con- 

 taining wolframite. The gangue is mainly quartz, the rhodochrosite 



