Idaho Maryland Mine History
The Idaho-Maryland Mine, located in the Grass Valley mining district of northern California was one of the most productive and best known gold mines in the Unites States, with gold production from the property dating back to 1863.
The Idaho-Maryland Mine, as it now exists, represents a consolidation of a number of important early day producing mines including Eureka, Idaho, Maryland, Brunswick, and Union Hill Mines. Based on historic production records, the I-M Mine produced a total of 2.4M oz gold at an average mill head grade of approximately 0.5oz/ton (17.1gpt). The I-M Mine was reportedly the second largest gold mine in the United States in 1941 (Clark, 2005), producing up to 129,000 oz gold per year before being forced to shut down by the US government in 1942 (Shore, 1943). Due to lack of development, a decline in gold production was experienced and recovery from war-time shutdown never occurred.
The Idaho-Maryland Mine has a rich history of mining work completed between 1863 and 1956 by various operators. The Property and its comprehensive collection of original documents was rediscovered in 1990 and efforts were made to reopen the historic mine; however, the operator was unsuccessful due to inability to raise necessary funding in unfavourable market conditions. The information presented here within has drawn from the history previously described in multiple reports of the Property and Jack Clark’s book Gold in Quartz. Gold discovery, mining activity, and significant events, in addition to ownership of the property and ownership changes, are described chronologically for the important gold veins that constitute the Idaho-Maryland Mine Property.