Open Pit, or Open Cast Mining

Courtesy of the Nevada Historic Preservation Office.

The design of the Houston Mineral and Oil open pit called for the destruction of many of Gold Hill's historic homes and its 120 year-old road. The price of gold slipped and work ceased in the early 1980s.

Photograph by Ronald M. James.

The Ophir Pit is the site of the June 1859 strike that led to founding the Comstock Mining District and Virginia City. Within a few months, after early miners dug the pit so deep the side walls became threatening, they began working underground.

Photograph by Arthur Rothstein. Courtesy of Library of Congress Prints and Photographs Division.

Workers sitting at the edge of a copper pit. Ruth, Nevada.

Courtesy of the Nevada Historic Preservation Office.

Free mining without restrictions could result in adverse environmental effects. Red Watson, a Comstock artist, depicted a future Virginia City, isolated by extensive open pit mining and no reclamation (ca. 1980).

Mining is a practical industry that seeks efficient ways to extracts mineral wealth from the ground. During the nineteenth century, precious metals deeper than about three hundred feet called for underground drift or hardrock mining.

Occasionally, ore bodies sufficiently close to the surface made open pit or open cast mining practical. Often regarded as a twentieth-century approach, open pit mining was actually widespread earlier. It was a logical extension of placer mining, which excavated into sand bars any number of feet. Digging deeper resulted in pits, a practice pursued with devastating effect in California where hydraulic mining eroded soil and silted the Sacramento River and San Francisco Bay.

In Nevada, open pits first appeared with the discovery of the Comstock Lode in 1859. Miners developed the Ophir Pit, site of the original Virginia City strike, immediately following the mining district's founding. Twentieth-century miners expanded the pit, but much of what is there today dates to 1860. Such excavations are often called "glory holes."

During the twentieth century, large heavy equipment and better engineered sidewalls resulted in open pits that dwarfed their predecessors. They are, nevertheless, based on an earlier, widely-employed prototype.

Further Reading

Otis E. Young. Western Mining: An Informal Account of Precious-metals Prospecting, Placering, Lode Mining, and Milling of the American Frontier from Spanish Times to 1893. Norman, OK: University of Oklahoma Press, 1970.
Ronald M. James. The Roar and the Silence: A History of Virginia City and the Comstock Lode. Reno, NV: University of Nevada Press, 1998.

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