184 THE VERMILION IRON-BEARING DISTRICT. 



extent by the use of picks. The fragments of the breccia are, however, the 

 same hard ore that occurs in the other mines of the district, but as a result 

 of the brecciation, a gi'eat deal of very finely comminuted ore is associated 

 with the larger fragments and occurs between them. The cause of the 

 brecciated condition of this ore will be discussed more at length under the 

 heading " Ore deposits." 



The ores of the district are rendered impure by various mechanical 

 mixtures of quartz, calcite, chlorite, iron pyrites, native copper, the oxide 

 of copper (cuprite), and the carbonates (malachite and azurite). These 

 copper "ores are present in very small quantity, however, and are of chief 

 interest on account of the fact that this occurrence of these minerals in 

 association with the ores at Soudan is the first recorded from the Lake 

 Superior region." Mr. Pengilly informed the writer that native copper had 

 been found in the Chandler mine several years prior to its known occur- 

 rence at Soudan. Quartz, calcite, chlorite, and pyrite occur locally, but in 

 considerable quantity, and as a result large quantities of ore are thrown 

 away in the attempt to get rid of these impurities. Grood hand specimens 

 showing these minerals can always be obtained from the dump piles and 

 even the stock piles of the Soudan mines. The minerals occur along the 

 walls of vugs of various sizes which exist in the ore bodies. 



The iron content of the Vermilion iron ores, computed from cargo 

 analyses made during 1899, varies from 60.47 to 67.37 per cent, and 

 averages about 63.7 per cent. The phosphorus content varies from 0.04 to 

 0.131 per cent, and averages about 0.057 per cent. The silica content 

 varies from 2.55 to 7.67 per cent, and averages 4.78 per cent. The water 

 content varies from 1.04 to 7.956 per cent, and averag'es about 5.50 per 

 cent. The ore bodies are of such importance that their origin, the 

 occurrence of the ore in them, etc., will be considered in detail under 

 separate headings. 



The physical character of the ores is such as to make them much desired 

 by the smelters for admixture with the softer, finer-grained ores. The ores 

 are hard and are obtained in large pieces and run through crushers and 



"The occurrence of copper minerals in hematite ore, Montana mine, Soudan, Minnesota; .descrip- 

 tion of the occurrence, by J. H. Eby; study of the minerals, by C. P. Berkey: Trans. Lake Superior 

 Mining Institute, Vol. IV, 1896, pp. 69-79. 



