In 1998, the Division of Mine Reclamation (DMR) began inventorying abandoned mined lands as part of a program to produce a report describing the "scope and magnitude" of abandoned mine issues in California. To support this effort, DMR began digitizing mining features from scanned USGS topographic quadrangles. Each of the 7.5-minute USGS topographic quadrangles was examined and all mining features were digitized and annotated with information derived from the map. In 2001, DMR completed the digitizing process for all 7.5-minute topographic quadrangles covering the state.
Geospatial data and an interactive map are currently located and maintained on the U.S. Geological Survey (USGS) Prospect and Mine Related Features dataset at https://mrdata.usgs.gov/usmin/map-us.html (zoom in for California features). Other information on abandoned mines or mining claims is potentially also available from the following sources.
- https://www.conservation.ca.gov/cgs/library – This is the website for the California Geological Survey (CGS; formerly California Division of Mines and Geology [CDMG]) library. If you are interested in the history, production, or other specifics of a named mine, a good place to look is the yearly Report of the State Mineralogist (published from the 1880s to the 1950s) and the County Reports of the CDMG. They are organized by County, then Commodity, then Mine Name. The descriptions usually include basic location information. These publications are available in some libraries, and certain ones can be found online. The most complete set of these publications plus other resources (such as CDMG Mineral Bulletins, which are collections of data on a specific commodity [e.g., gold, chromium, copper, etc.]) are in the CGS Library in Sacramento.
- The Bureau of Land Management Locatable Minerals website (https://www.blm.gov/programs/energy-and-minerals/mining-and-minerals/locatable-minerals) and Navigator website (https://navigator.blm.gov/home) provide information related to public lands.
- You may be able to find if a claim was recorded or if bound volumes of mine patents, claims, or other records exist by visiting local historical societies or a county recorder's or assessor's offices.
- Queries of known mine names at www.mindat.org (using the “Locality Search" on the far-right side of the page can return a list of publications that mention the mine) or through general web searches.