THE MINERALS OF IDAHO 233 



also in disseminated form. It would not be surprising to find that 

 the carbonate associated with folding and Assuring in the mineralized 

 area is siderite and that the disseminated carbonate uniformly dis- 

 tributed in sedimentary beds remote from mineralizing influences 

 is ankerite. 



The material has not been available for definite chemical research 

 on the disseminated carbonates. 



In addition to the siderite gangue of the galena ores of the pro- 

 ducing mines there have long been mentioned great barren ledges of 

 siderite or siderite veins carrying chalcopyrite making a copper ore 

 usually too low grade for profitable exploitation. Umpleby and 

 Jones 50 give especial attention to these and divide them into three 

 groups, the southern area, south of South Fork of the Coeur d'Alene 

 River; second, deposits in diabase along St. Joe River; and third, 

 deposits north of the South Fork of the Coeur d'Alene River, prin- 

 cipally along the Little North Fork of the river. The first group is 

 the largest and out of 12 veins which are specifically described as 

 typical large siderite veins, the Monitor, Richmond, Manhattan, 

 Park, Reindeer Queen, Carney Copper, Vienna-International, Castle 

 Rock, Smart Aleck, Horn Silver, Colusa, Black Diamond, and Palis- 

 ade, the gangue carbonates from six have been analyzed. These are 

 the Monitor, Richmond, Manhattan, Reindeer Queen, Carney Cop- 

 per, and Castle Rock. Of these the first five named are ankerite- 

 chalcopyrite veins, while the sixth, the Castle Rock, on Placer 

 Creek, is a siderite-galena vein. There must be two kinds of car- 

 bonate veins represented in this area. The Vienna-International, 

 Smart Aleck, and Horn Silver probably also belong to the siderite 

 type. The Palisade, Colusa, and Black Diamond at the head of 

 Pine Creek probably also are siderite veins to judge from their high 

 manganese content. 



The writer is not familiar with the prospects along the St. Joe River 

 and has not examined specimens from the deposits mentioned in this 

 area in the report above cited. Two specimens from this area which 

 were analyzed proved to be ankerities. 



Regarding the nature of the gangue in the prospects on the Little 

 North Fork, little definite information is available. No specimens 

 of primary ore from the Empire (formerly Horst-Powell) mine have 

 been available for examination. The writer, in a brief examination 

 of the Hamburg-American and Handspike claims, saw no carbonate. 

 Large specimens of a carbonate from the Riverside have the appear- 

 ance of siderite. 



While the writer does not favor the minor refinements of vein 

 classification which subdivide a period of mineralization into a large 



50 J. B. Umpleby and E. L. Jones, jr. Geology and ore deposits of Shoshone County, Idaho. U. S. 

 Geol. Survey, Bull. 732, pp. 110- 115, L923. 



