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Abandoned mines › Colorado
Abandoned mine inventory

Abandoned mines in Custer County, Colorado

Custer County, Colorado has 2,062 mine and prospect features on USGS topographic maps published 1954–2001, including 38 mine openings (shafts, adits and air shafts) and 1,999 prospect pits; 9 of the features carry a name on the map. OSMRE's abandoned mine land inventory lists 4 problems in the county, 2 of them not yet reclaimed. MSHA's register carries 7 mines in the county with status Abandoned or Abandoned and Sealed.

Every mine and prospect feature the USGS digitized from historical topographic maps covering Custer 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)
2,062
Mine openings
38
OSMRE problems unreclaimed
2
MSHA mines marked abandoned
7
9 features carry a name1,999 prospect pits16 quadrangle maps, published 1954–2001 4 OSMRE problems, 2 reclaimed 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
    42 2.0%
  2. Prospect pits and trenches
    shallow exploration diggings that never became a mine
    1,999 96.8%
  3. Mines and surface workings
    labelled mines, open pits, strip mines, placer and hydraulic workings
    10 0.5%
  4. Quarries, gravel and borrow pits
    construction-material and industrial-mineral extraction
    15 0.7%
Named features on the maps9 named · from the USGS compilation
Name on map Feature
Bassick Mine Adit
Bull Domingo Mine Mine Shaft
Cloverdale Mine Adit
Cloverdale Mine Adit
Defender Mine Mine Shaft
Herman Passiflora/Songbird Mine Mine Shaft
Perlite Quarry Quarry
Rita Alta Mine Adit
Rita Alta 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.

OSMRE abandoned mine land problems4 on inventory
Problem area Problem Status
Custer - Non-coal-county-wide P1 Portals In Reclamation
Custer - Non-coal-county-wide P1 Portals Reclamation Completed
Custer - Non-coal-county-wide P1 Vertical Openings In Reclamation
Custer - Non-coal-county-wide P1 Vertical Openings Reclamation Completed

Problem types carry OSMRE's priority prefix: P1 and P2 are threats to health, safety and property, P3 is environmental. A problem area is a cluster of problems reclaimed as one project; several rows can share one location.

MSHA-registered mines with status Abandoned7 on register
  1. Custer County Pit No 1
    Surface metal/non-metal · Colorado Department Of Highways · MSHA ID 0503492
    Abandoned
  2. Persolite Products-Rosita Pit
    Surface metal/non-metal · Persolite Products Inc · MSHA ID 0500430
    Abandoned
  3. Polonia Mine & Mill
    Facility metal/non-metal · Polonia Mining Company · MSHA ID 0503897
    Abandoned
  4. Portable Unit #4
    Surface metal/non-metal · Colorado Quarries Inc · MSHA ID 0504198
    Abandoned
  5. Screening Plant
    Surface metal/non-metal · Custer County Road & Bridge · MSHA ID 0504668
    Abandoned
  6. Shaun Lode
    Underground metal/non-metal · Griffin & Mc Creight Mining Company · MSHA ID 0503728
    Abandoned
  7. State Land Board
    Surface metal/non-metal · Colorado Department Of Highways · MSHA ID 0503328
    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
Prospect Pit 1,999
Mine Shaft 20
Adit 18
Open Pit Mine 7
Gravel Pit 4
Quarry 4
Borrow Pit 4
P1 Vertical Openings 2
P1 Portals 2
Strip Mine 2
Gravel Pit 2
Quarry 1
Open Pit Mine or Quarry 1
Other counties in ColoradoAll 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.