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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 relations.

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 mammillary or stalactitic forms, and it sometimes shows apparent signs of bedding. In places it is soft, earthy and pulverulent and contains angular fragments of sandstone, shale and limestone from a small fraction of an inch to several inches in diameter. Sometimes 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 110°-115° Centigrade.