A PLEISTOCENE MANGANESE DEPOSIT NEAR 

 GOLCONDA, NEVADA.^ 



THE LOCATION OF THE DEPOSIT, 



GoLCONDA is a small settlement in northern Nevada, in the 

 valley of the Humboldt river, on the line of the Central Pacific 

 Railroad. A deposit of manganese ore occurs about three miles 

 northeast of the town, on a part of the Havallah Range locally 

 known as the Edna Mountains, and a short distance south of 

 where the Humboldt river has cut its channel through the range. 

 The deposit is small and of no great commercial value, but it is 

 of interest both in the nature of the ore and in its geologic rela- 

 tions. 



THE NATURE OF THE ORE. 



The ore is a massive, black, glossy oxide of manganese with 

 a hardness varying from 3 to 4. It is generally of a more or 

 less porous structure, often containing cavities lined with mammil- 

 lary or stalactitic forms, and it sometimes shows apparent signs 

 of bedding. In places it is soft, earthy and pulverulent and con- 

 tains angular fragments of sandstone, shale and limestone from 

 a small fraction of an inch to several inches in diameter. Some- 

 times it is stained brown by iron. 



The following analysis by R. N. Brackett, Chemist of the 

 Geological Survey of Arkansas, shows the composition of a 

 specimen of this ore dried at iio°-ii5° Centigrade. 



Analysis of Manganese Ore from near Golconda, Nevada. 

 Manganese protoxide (MnO) - - 65.66 



Oxygen (O) - - - - 10.31 



Ferric oxide (FeoO 3 ) - - - 3.32 



' This deposit was examined by the writer while investigating the manganese 

 resources of the United States and Canada for the Geological Survey of Arkansas, 

 and was first described in Vol. I. of the Geological Survey of Arkansas for 1890, J. 

 C. Branner, State Geologist, R. A. F. Penrose, Jr., Assistant Geologist. 



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