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Abandoned mines › California
Abandoned mine inventory

Abandoned mines in Santa Clara County, California

Santa Clara County, California has 322 mine and prospect features on USGS topographic maps published 1917–1994, including 107 mine openings (shafts, adits and air shafts) and 44 prospect pits; 20 of the features carry a name on the map. MSHA's register carries 23 mines in the county with status Abandoned or Abandoned and Sealed.

Every mine and prospect feature the USGS digitized from historical topographic maps covering Santa Clara County, every OSMRE abandoned mine land problem in the county, and every MSHA-registered mine here with status Abandoned. Named features are listed below; unnamed ones are counted by type. Locations are deliberately not shown: this page says what abandoned workings are in the county, not where to find them. They are dangerous and should not be entered.

Mapped mine features (USGS)
322
Mine openings
107
OSMRE problems unreclaimed
0
MSHA mines marked abandoned
23
20 features carry a name44 prospect pits23 quadrangle maps, published 1917–1994 0 MSHA mines abandoned and sealed
What the features are
  1. Mine openings
    shafts, adits, air shafts, portals and vertical openings: the ways into underground workings
    107 33.2%
  2. Prospect pits and trenches
    shallow exploration diggings that never became a mine
    44 13.7%
  3. Mines and surface workings
    labelled mines, open pits, strip mines, placer and hydraulic workings
    28 8.7%
  4. Quarries, gravel and borrow pits
    construction-material and industrial-mineral extraction
    105 32.6%
  5. Dumps, tailings, spoil and gob
    what mining left above ground
    38 11.8%
Named features on the maps20 named · from the USGS compilation
Name on map Feature
America Mine Adit
Bernal Mine Mine Shaft
Day Tunnel Adit
Enriquita Mine Adit
Greystone Quarry Quarry
Guadalupe Mines Mine Shaft
Hacienda Tunnel Adit
Hillsdale Mine Adit
New Almaden Mine Mine Shaft
New North Almaden Mine Adit
New North Almaden Mine Adit
Randol Tunnel Adit
San Antonio Mine Adit
Santa Teresa Mine Adit
Santa Ysabel Shaft Mine Shaft
Senator Mine Mine Shaft
St George Shaft Mine Shaft
Sunset Quarry Quarry
Western Mines Mine Shaft
Westvaco Mine Mine

A name is the label printed beside the symbol on the map. "First mapped" is the earliest topographic edition that shows the symbol, which bounds the feature's age from above; it is not the date it was worked. Unnamed features (most prospect pits, adits and shafts carry no label) are in the counts above but not this list.

MSHA-registered mines with status Abandoned23 on register
  1. AZEVEDO QUARRY
    Surface metal/non-metal · Azevedo Quarry · MSHA ID 0404131
    Abandoned
  2. Brems Pit
    Surface metal/non-metal · Brems Sand & Gravel · MSHA ID 0401708
    Abandoned
  3. Calaveras Rock Incorporated
    Surface metal/non-metal · Calaveras Rock Inc · MSHA ID 0402280
    Abandoned
  4. Curtner Pit
    Surface metal/non-metal · Freeman-Sondgroth · MSHA ID 0403827
    Abandoned
  5. Freeman Quarry
    Surface metal/non-metal · Granite Construction Company · MSHA ID 0405448
    Abandoned
  6. Hellyer Pit
    Surface metal/non-metal · Max Abbott · MSHA ID 0403860
    Abandoned
  7. Hillsdale Pit And Mill Plant
    Surface metal/non-metal · Hillsdale Rock Company · MSHA ID 0400136
    Abandoned
  8. Hubble Quarry And Mill
    Surface metal/non-metal · Piazza Construction Company · MSHA ID 0402268
    Abandoned
  9. Hubble Sand & Gravel Pit & Mill
    Surface metal/non-metal · Piazza Construction Company · MSHA ID 0401837
    Abandoned
  10. Lehigh Permanente Quarry
    Surface metal/non-metal · Lehigh Southwest Cement Co. · MSHA ID 0400158
    Abandoned
  11. Metcalf Plant No 2
    Surface metal/non-metal · Hillsdale Rock Company · MSHA ID 0402882
    Abandoned
  12. Mt View
    Surface metal/non-metal · Kaiser Sand & Gravel Company · MSHA ID 0403351
    Abandoned
  13. Page Quarry And Mill
    Surface metal/non-metal · Page Mill Quarry Corp · MSHA ID 0400215
    Abandoned
  14. Patton Quarry And Mill
    Surface metal/non-metal · Patton Brothers Inc · MSHA ID 0400205
    Abandoned
  15. Permanente Quarry
    Surface metal/non-metal · Kaiser Cement Corp · MSHA ID 0404353
    Abandoned
  16. Permanente Rock Plant
    Facility metal/non-metal · Lehigh Southwest Cement Company · MSHA ID 0405870
    Abandoned
  17. Portable #2
    Surface metal/non-metal · Kroeker Inc · MSHA ID 0405824
    Abandoned
  18. PORTABLE EXTEC
    Surface metal/non-metal · TMT ENTERPRISES, INC. · MSHA ID 0405788
    Abandoned
  19. Portable Rascal
    Surface metal/non-metal · TMT Enterprises, Inc. · MSHA ID 0405849
    Abandoned
  20. RAISCH PRODUCTS
    Facility metal/non-metal · Raisch Products · MSHA ID 0405049
    Abandoned
  21. Road Builders Pit
    Surface metal/non-metal · Thomas R Bess · MSHA ID 0404111
    Abandoned
  22. SERPA PIT QUARRY
    Surface metal/non-metal · Raisch Products · MSHA ID 0402880
    Abandoned
  23. Western Tile Sand & Gravel
    Surface metal/non-metal · Western Tile & Supply Company · MSHA ID 0402000
    Abandoned

Status and date are as reported to MSHA by the operator. Each mine's own page carries its accident, citation and inspection record.

By source vocabularythe publishers' own terms
Feature type Features
Adit 70
Prospect Pit 44
Gravel Pit 42
Mine Shaft 37
Quarry 27
Open Pit Mine or Quarry 21
Tailings - Undifferentiated 20
Salt Evaporator 11
Gravel/Borrow Pit - Undifferentiated 10
Gravel Pit 8
Mine Dump 7
Quarry - Limestone 6
Quarry 5
Open Pit Mine 4
Clay Pit 3
Borrow Pit 3
Disturbed Surface 1
Mine 1
Borrow Pit 1
Disturbed Surface - Pit 1
Other counties in CaliforniaAll counties →
How to read these numbers

A USGS feature is a symbol on a historical topographic map, there when the map was surveyed; it may since have been sealed, reclaimed, built over or reopened as a working mine, and the map does not say which. An OSMRE row is a problem the abandoned mine land program tracks, not a mine. An MSHA mine is a registered operation whose operator reported abandonment, a record that starts in the 1970s. The three overlap and are never added together. The county is assigned from each feature's coordinates against the Census 2023 county boundaries. The full method is on the national page.

Sources
  1. USGS, Consolidated Prospect- and Mine-Related Features from 7.5- and 15-Minute Topographic Quadrangle Maps of the United States (USMIN)
    597,612 point and area features digitized from about 106,350 historical topographic maps published 1886–2006; public domain (CC0). A feature is a map symbol, not a field-verified site, and the map does not say whether it was still worked.
  2. USGS Fact Sheet 2025–3003, The Abandoned Mine Inventory of the United States
    States that as of 2025 there is no comprehensive national inventory of abandoned mine features, and that the detailed national database now being built will not be published.
  3. OSMRE, Abandoned Mine Land Inventory System (e-AMLIS), public Problems layer
    One row per abandoned mine land problem in a problem area, with its type, funding program and reclamation status; mostly coal mined before the 1977 Surface Mining Control and Reclamation Act. Coordinates are the problem area's.
  4. MSHA, Mines dataset (Mine Data Retrieval System)
    Every mine registered with MSHA since the 1970s; a mine reads Abandoned or Abandoned and Sealed when its operator reported that status. Refreshed weekly.
  5. US Census Bureau, 2023 cartographic county boundaries (1:500,000)
    Each feature's county is assigned by its coordinates against these boundaries, not copied from the source file.
  6. GAO-20-238, Abandoned Hardrock Mines (March 2020)
    Federal agencies had identified at least 140,000 abandoned hardrock mine features on federal land and estimated more than 390,000 more not yet captured in their databases.
  7. Abandoned Hardrock Mine Reclamation (AHMR) Program, US Department of the Interior
    The program the USGS inventory is compiled for. Its appropriations and the 674,000 field-confirmed feature count on this page were provided by the program manager, Office of Environmental Policy and Compliance, and are cited with permission (2026-09-08).
  8. IMCC-NAAMLP Hardrock AML Report
    Page 48 carries the two figures this page leans on: USGS estimates 633,181 of the 725,690 mine features it recorded from historic topographic maps, 87 percent, are hardrock; and state and federal agencies have submitted more than 724,000 AML features to the national database being built, already more than the historic maps hold. Year-by-year AHMR funding is on page 35.