Abandoned mines in San Benito County, California

1. Mine openings

   shafts, adits, air shafts, portals and vertical openings: the ways into underground workings
   79 16.0%
2. Prospect pits and trenches

   shallow exploration diggings that never became a mine
   301 61.1%
3. Mines and surface workings

   labelled mines, open pits, strip mines, placer and hydraulic workings
   57 11.6%
4. Quarries, gravel and borrow pits

   construction-material and industrial-mineral extraction
   49 9.9%
5. Dumps, tailings, spoil and gob

   what mining left above ground
   7 1.4%

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.

1. Anzar Quarry

   Surface metal/non-metal · South Bay Sand & Gravel · MSHA ID 0404919
   Abandoned 1988-08-23
2. Bitterwater Quarry

   Surface metal/non-metal · Parsons Ag Minerals · MSHA ID 0404961
   Abandoned 1990-07-27
3. Cienega Pit And Mill

   Surface metal/non-metal · Don Rider & Son · MSHA ID 0401752
   Abandoned 1979-02-06
4. Harrison Ranch Limestone Quarry

   Surface metal/non-metal · Granite Rock Company · MSHA ID 0404899
   Abandoned 1988-09-02
5. Hillsdale Paicines Pit

   Surface metal/non-metal · Custom Rock Products Inc · MSHA ID 0404658
   Abandoned 1985-09-18
6. JOE 5 PIT

   Surface metal/non-metal · Kcac Inc · MSHA ID 0402550
   Abandoned 2002-12-05
7. Mule Shoe Mine

   Facility metal/non-metal · Buffalo Gypsum Inc · MSHA ID 0405250
   Abandoned 2018-12-01
8. New Idria Mines

   Surface metal/non-metal · Idria Minerals Corp · MSHA ID 0402609
   Abandoned 1981-07-16
9. Pacheco Pit

   Surface metal/non-metal · Granite Construction Company · MSHA ID 0404714
   Abandoned 1988-08-29
10. PAICINES PIT

    Surface metal/non-metal · San Benito Supply · MSHA ID 0404646
    Abandoned 1999-02-02
11. Paicines Plant

    Surface metal/non-metal · Hillsdale Rock Company · MSHA ID 0404948
    Abandoned 1991-06-17
12. Paicines Plant No 7

    Surface metal/non-metal · Hillsdale Rock Company · MSHA ID 0404252
    Abandoned 1980-09-30
13. Paicines Quarry

    Surface metal/non-metal · South Bay Sand & Gravel · MSHA ID 0404920
    Abandoned 1988-08-23
14. Pearce Quarry

    Surface metal/non-metal · Grade-Way Construction · MSHA ID 0404736
    Abandoned 1986-01-03
15. San Benito Sand Plant

    Surface metal/non-metal · Granite Rock Company · MSHA ID 0404270
    Abandoned 1992-04-14
16. San Juan Asphalt

    Surface metal/non-metal · San Juan Asphalt · MSHA ID 0404896
    Abandoned 1994-08-29
17. San Juan Pit

    Surface metal/non-metal · Evergreen Concrete Inc · MSHA ID 0404340
    Abandoned 1989-02-09
18. San Juan Pit Mill

    Surface metal/non-metal · Hillsdale Rock Company Inc · MSHA ID 0402781
    Abandoned 2007-12-07
19. San Juan Sand Pit

    Surface metal/non-metal · William Caprista Underground Construction Inc · MSHA ID 0404325
    Abandoned 1982-08-09
20. SANDMAN INC.

    Surface metal/non-metal · Star Concrete · MSHA ID 0401809
    Abandoned 1997-08-01
21. Vallecitos Clay Mine

    Surface metal/non-metal · Leonard W Knepper · MSHA ID 0400606
    Abandoned 1982-08-09
22. Williams Sand Pit

    Surface metal/non-metal · Mel Williams Sand & Gravel Inc · MSHA ID 0403817
    Abandoned 1982-08-09

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

• San Bernardino County 14,976
• Inyo County 11,475
• Kern County 4,879
• Riverside County 3,227
• Mono County 2,946
• Siskiyou County 2,362
• Imperial County 1,232
• Mariposa County 1,079
• Tuolumne County 948
• San Diego County 901
• Calaveras County 840
• Shasta County 832

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.