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Abandoned mines › California
Abandoned mine inventory

Abandoned mines in Monterey County, California

Monterey County, California has 166 mine and prospect features on USGS topographic maps published 1919–1995, including 34 mine openings (shafts, adits and air shafts) and 28 prospect pits; 18 of the features carry a name on the map. MSHA's register carries 28 mines in the county with status Abandoned or Abandoned and Sealed.

Every mine and prospect feature the USGS digitized from historical topographic maps covering Monterey 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)
166
Mine openings
34
OSMRE problems unreclaimed
0
MSHA mines marked abandoned
28
18 features carry a name28 prospect pits30 quadrangle maps, published 1919–1995 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
    34 20.5%
  2. Prospect pits and trenches
    shallow exploration diggings that never became a mine
    28 16.9%
  3. Mines and surface workings
    labelled mines, open pits, strip mines, placer and hydraulic workings
    67 40.4%
  4. Quarries, gravel and borrow pits
    construction-material and industrial-mineral extraction
    35 21.1%
  5. Dumps, tailings, spoil and gob
    what mining left above ground
    2 1.2%
Named features on the maps18 named · from the USGS compilation
Name on map Feature
Buclimo Mine Open Pit Mine
Buclimo Mine Open Pit Mine
Calizona Mine Mine
Gorda Mine Mine
Los Burros Mine Open Pit Mine
Melville Mine Mine
Melville Mine Open Pit Mine
Pacific Coast Aggregates Co Plant No 10 Open Pit Mine or Quarry
Patriquin Mine Mine
Patriquin Quicksilver Mine Open Pit Mine
Poppy Mine Open Pit Mine
Quicksilver Mine Open Pit Mine
Sommers Prospect Prospect Pit
Stone Canyon Mine Mine
Stone Canyon Mine Mine
Stone Canyon Mine Mine Shaft
White Mine Adit
White Mine Adit

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 Abandoned28 on register
  1. ARROYO SECO PIT
    Surface metal/non-metal · Wm J Clark Trucking Service Inc · MSHA ID 0405025
    Abandoned
  2. Bradley Plant
    Surface metal/non-metal · Calportland Construction · MSHA ID 0405572
    Abandoned
  3. BRADLEY PLANT & BORROW PIT
    Surface metal/non-metal · Madonna Construction Company · MSHA ID 0405184
    Abandoned
  4. CHALONE CREEK RESOURCES
    Surface metal/non-metal · Swift Tectonics Inc · MSHA ID 0405412
    Abandoned
  5. Chalone Pits And Mills
    Surface metal/non-metal · King City Transit Mix Inc · MSHA ID 0401857
    Abandoned
  6. Chieftan Power Screen
    Facility metal/non-metal · Swift Tectonics Inc · MSHA ID 0405411
    Abandoned
  7. County Pits And Mill
    Surface metal/non-metal · Monterey County Road Department · MSHA ID 0401529
    Abandoned
  8. Del Monte Quarry
    Surface metal/non-metal · Granite Construction Co · MSHA ID 0400087
    Abandoned
  9. Dennis Ponte Incorporated Portable
    Surface metal/non-metal · Dennis Ponte Inc · MSHA ID 0405167
    Abandoned
  10. Dolomite Materials Branch
    Surface metal/non-metal · Granite Rock Company · MSHA ID 0405158
    Abandoned
  11. ECHENIQUE PIT
    Surface metal/non-metal · Swift Tectonics Inc · MSHA ID 0405413
    Abandoned
  12. Fleming Pit
    Surface metal/non-metal · Los Laureles Granite Co · MSHA ID 0400182
    Abandoned
  13. Hilltown Bar
    Surface metal/non-metal · T J Smith Company · MSHA ID 0403795
    Abandoned
  14. King City Mill
    Facility metal/non-metal · KCAC Inc · MSHA ID 0401062
    Abandoned
  15. Lapis Plant
    Surface metal/non-metal · Cemex Construction Materials Pacific LLC · MSHA ID 0402843
    Abandoned
  16. Marina Dryer & Dredge
    Facility metal/non-metal · Monterey Sand Company Inc · MSHA ID 0403797
    Abandoned
  17. Marina Pit And Mill
    Surface metal/non-metal · Monterey Sand Company Inc · MSHA ID 0401861
    Abandoned
  18. Mariposa Mine
    Underground metal/non-metal · Myron John Koenig · MSHA ID 0401333
    Abandoned
  19. Metz Plant
    Surface metal/non-metal · Granite Construction Co · MSHA ID 0404517
    Abandoned
  20. PANCHO RICO SAND AND GRAVEL
    Surface metal/non-metal · SWIFT TECTONICS, INC. · MSHA ID 0405624
    Abandoned
  21. Parker Canyon
    Surface metal/non-metal · Henningsen Construction Company · MSHA ID 0400132
    Abandoned
  22. Pico Blanco
    Surface metal/non-metal · Granite Rock Company · MSHA ID 0404544
    Abandoned
  23. Prattco
    Surface metal/non-metal · Lone Star Industries Inc · MSHA ID 0401899
    Abandoned
  24. Sand City Beach Plant
    Surface metal/non-metal · Monterey Sand Company Inc · MSHA ID 0404876
    Abandoned
  25. Sand City Dryer
    Facility metal/non-metal · Monterey Sand Company Inc · MSHA ID 0403796
    Abandoned
  26. Sand City Pit And Mill
    Surface metal/non-metal · Monterey Sand Company Inc · MSHA ID 0401862
    Abandoned
  27. Soledad Quarry
    Surface metal/non-metal · Syar Industries Inc · MSHA ID 0404906
    Abandoned
  28. Valley Rock And Sand Plant
    Surface metal/non-metal · Valley Rock & Sand Company · MSHA ID 0401994
    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
Open Pit Mine or Quarry 43
Adit 32
Prospect Pit 28
Gravel Pit 15
Open Pit Mine 8
Quarry 8
Disturbed Surface 6
Mine 6
Gravel Pit 4
Open Pit Mine or Quarry 4
Sand Pit 3
Borrow Pit 3
Tailings - Pond 2
Mine Shaft 2
Quarry 2
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.