Miners about to descend into the Empire Gold Mine, Grass Valley, California, ca.1900-1930 

A group of miners assembled on inclined tram ready to descend to 2300-ft level of gold mine, Grass Valley, California, before 1906 

View of Main Street in Grass Valley, ca.1930 

Two men posing on a trolley-line engine for hauling ore cars, Grass Valley, northern California, ca.1900 

View of Mill Street in Grass Valley, Yerba County, ca.1930 

Miner's pack animals in front of mining supply stores, Goldfield, Nevada, ca.1900 

Interior view of mine and miners in the Mohawk Mine, Goldfield, Nevada, ca.1900-1905 

Miners working in a mine shaft, [s.d.] 

A miner using hydraulic mining techniques and tools to mine, Nevada City, California, ca.1900-1930 

Exterior view Murchie Gold Mine in Nevada City, Nevada, 1907 

Miners relaxing in a mine shaft, [s.d.] 

Old mill used by miners at the Ten Stamps Mine, ca.1900 

View of the Placer mine at Big Bar, Trinity County, showing a man with mining apparatus, 1900-1910 

View of the Oustomah gold mine in Nevada City, 1907 

Complex of buildings at the Empire Mine in Grass Valley, ca.1910 

Hydraulic Big Bar Placer Mine site, Trinity, 1906 (ca.1930?) 

View of the landscaped grounds of the Empire Mine in Grass Valley, ca.1910 

Three miners, wearing prospector outfits, standing next to a burro cart loaded with camp supplies, Goldfield, Nevada, ca.1900-1905 

View of the Champion Mines in Nevada City, ca.1930 

A miner's cabin built from bottles, Goldfield, Nevada, ca.1900-1930