Bentonite mines in the US: 31 open mines and MSHA citations
MSHA lists 31 open bentonite mines in the US, run by 10 operators and employing 648 people. Since January 1, 2022 its inspectors issued 636 citations and orders there with $206,189 in proposed penalties, and operators reported 119 injury or illness cases. The operators with the most open mines are Black Hills Bentonite-A Limited Liability Co; American Colloid Company Mineral Group; Wyo-Ben, Inc. Data from MSHA, November 6, 2026.
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- Open mines
- 31
- Operators
- 10
- Employees
- 648
- Active
- 23
- Intermittent
- 5
- Temporarily Idled
- 3
- Citations and orders since January 1, 2022
- 636
- Significant and substantial
- 117 (18.4%)
- Closure orders
- 5
- High negligence or reckless
- 28
- Proposed penalties
- $206,189
- Amount paid so far
- $192,254
- Inspections
- 353
- Inspector hours on site
- 3,135
- Citations per inspection
- 1.80 (all mines 2.30)
- Accident reports
- 122
- Injury and illness cases
- 119
- Fatalities
- 0
- Latest MSHA record
- November 5, 2026
Operators with the most open mines
Ranked by open mines, then by citations. Sole proprietors and individuals are not listed.
| Operator | Open mines | Employees | Citations since 2022 | Proposed penalties | Injury cases |
|---|---|---|---|---|---|
| Black Hills Bentonite-A Limited Liability Co | 8 | 78 | 224 | $68,438 | 41 |
| American Colloid Company Mineral Group | 6 | 204 | 147 | $46,866 | 35 |
| Wyo-Ben, Inc | 6 | 157 | 83 | $17,018 | 31 |
| Bentonite Performance Minerals, LLC | 3 | 155 | 62 | $11,254 | 8 |
| Tolsa Wyoming Bentonite Corp. | 2 | 9 | 85 | $56,892 | 1 |
| Imerys Minerals USA, Inc. | 2 | 17 | 13 | $1,856 | 2 |
| Central Oregon Bentonite Company | 1 | 3 | 12 | $2,443 | 0 |
| Protech Minerals, LLC | 1 | 1 | 10 | $1,422 | 0 |
| Brutill Construction, Inc | 1 | 2 | 0 | $0 | 0 |
| U.S. Silica Company, LLC | 1 | 22 | 0 | $0 | 1 |
Operators with the most citations
Citations and orders issued since January 1, 2022 at their open mines here.
| Operator | Open mines | Employees | Citations since 2022 | Proposed penalties | Injury cases |
|---|---|---|---|---|---|
| Black Hills Bentonite-A Limited Liability Co | 8 | 78 | 224 | $68,438 | 41 |
| American Colloid Company Mineral Group | 6 | 204 | 147 | $46,866 | 35 |
| Tolsa Wyoming Bentonite Corp. | 2 | 9 | 85 | $56,892 | 1 |
| Wyo-Ben, Inc | 6 | 157 | 83 | $17,018 | 31 |
| Bentonite Performance Minerals, LLC | 3 | 155 | 62 | $11,254 | 8 |
| Imerys Minerals USA, Inc. | 2 | 17 | 13 | $1,856 | 2 |
| Central Oregon Bentonite Company | 1 | 3 | 12 | $2,443 | 0 |
| Protech Minerals, LLC | 1 | 1 | 10 | $1,422 | 0 |
| Brutill Construction, Inc | 1 | 2 | 0 | $0 | 0 |
| U.S. Silica Company, LLC | 1 | 22 | 0 | $0 | 1 |
Mines with the most citations
Open mines, ranked by citations and orders since January 1, 2022.
| Mine | Operator | County | Main commodity | Employees | Citations since 2022 |
|---|---|---|---|---|---|
| Tolsa Wyoming Bentonite Plant | Tolsa Wyoming Bentonite Corp. | Natrona County, WY | Bentonite | 8 | 85 |
| Mills Plant | Black Hills Bentonite-A Limited Liability Co | Natrona County, WY | Bentonite | 20 | 54 |
| Lovell Mill | American Colloid Company Mineral Group | Big Horn County, WY | Bentonite | 44 | 52 |
| Belle/Colony Mine | American Colloid Company Mineral Group | Crook County, WY | Bentonite | 77 | 41 |
| Magnet Cove Mill | Wyo-Ben, Inc | Big Horn County, WY | Bentonite | 36 | 35 |
| BPM Colony Mill | Bentonite Performance Minerals, LLC | Crook County, WY | Bentonite | 70 | 34 |
| Kaycee Mine | Black Hills Bentonite-A Limited Liability Co | Johnson County, WY | Bentonite | 13 | 33 |
| Casper Plant | Black Hills Bentonite-A Limited Liability Co | Natrona County, WY | Bentonite | 12 | 30 |
| Tensleep Mine | Black Hills Bentonite-A Limited Liability Co | Washakie County, WY | Bentonite | 8 | 30 |
| BPM Lovell Mill | Bentonite Performance Minerals, LLC | Big Horn County, WY | Bentonite | 62 | 27 |
| Thornton Plant | Black Hills Bentonite-A Limited Liability Co | Weston County, WY | Bentonite | 1 | 26 |
| Colony West Mill | American Colloid Company Mineral Group | Crook County, WY | Bentonite | 30 | 23 |
| Worland Plant | Black Hills Bentonite-A Limited Liability Co | Washakie County, WY | Bentonite | 11 | 22 |
| Colony East Mill | American Colloid Company Mineral Group | Crook County, WY | Bentonite | 34 | 20 |
| HT Plant | Black Hills Bentonite-A Limited Liability Co | Natrona County, WY | Bentonite | 10 | 18 |
| Stucco Mill | Wyo-Ben, Inc | Big Horn County, WY | Bentonite | 30 | 16 |
| Sage Creek Mill | Wyo-Ben, Inc | Big Horn County, WY | Bentonite | 17 | 13 |
| Star #1-2-3 | Central Oregon Bentonite Company | Crook County, OR | Bentonite | 3 | 12 |
| Magnet Cove Mine | Wyo-Ben, Inc | Big Horn County, WY | Bentonite | 37 | 11 |
| Belle Fourche Mill | American Colloid Company Mineral Group | Butte County, SD | Bentonite | 5 | 11 |
| Oshoto Mine | Black Hills Bentonite-A Limited Liability Co | Weston County, WY | Bentonite | 3 | 11 |
| Brunswick Plant | Imerys Minerals USA, Inc. | Glynn County, GA | Bentonite | 10 | 10 |
| Ibex Bentonite | Protech Minerals, LLC | San Bernardino County, CA | Bentonite | 1 | 10 |
| Lucerne Mill | Wyo-Ben, Inc | Hot Springs County, WY | Bentonite | 26 | 6 |
| Aberdeen Mine | Imerys Minerals USA, Inc. | Monroe County, MS | Bentonite | 7 | 3 |
| Big Horn Basin Mines | Wyo-Ben, Inc | Big Horn County, WY | Bentonite | 11 | 2 |
| BPM Lovell Mine | Bentonite Performance Minerals, LLC | Big Horn County, WY | Bentonite | 23 | 1 |
| Fowlkes Mine | U.S. Silica Company, LLC | Monroe County, MS | Bentonite | 22 | 0 |
| Yellowtail Mine | American Colloid Company Mineral Group | Big Horn County, WY | Bentonite | 14 | 0 |
| Screen #4 | Brutill Construction, Inc | Johnson County, WY | Bentonite | 2 | 0 |
| Tolsa Mines | Tolsa Wyoming Bentonite Corp. | Natrona County, WY | Bentonite | 1 | 0 |
States
| State | Open mines | Share |
|---|---|---|
| Wyoming | 25 | 80.6% |
| Mississippi | 2 | 6.5% |
| California | 1 | 3.2% |
| Georgia | 1 | 3.2% |
| Oregon | 1 | 3.2% |
| South Dakota | 1 | 3.2% |
Citations and injury cases by year
Calendar years since 2022; 2026 runs to the date of the MSHA files.
| Year | Citations and orders | Significant and substantial | Proposed penalties | Injury and illness cases |
|---|---|---|---|---|
| 2022 | 162 | 44 | $63,431 | 21 |
| 2023 | 121 | 21 | $36,219 | 33 |
| 2024 | 204 | 37 | $78,692 | 28 |
| 2025 | 79 | 5 | $17,431 | 20 |
| 2026 | 70 | 10 | $10,416 | 17 |
Standards cited most at bentonite mines
Sections of Title 30 of the Code of Federal Regulations named on the citations, with the part each belongs to.
| Standard | What the part covers | Citations |
|---|---|---|
| 30 CFR 56.14100 | Surface metal and nonmetal mines | 47 |
| 30 CFR 56.14107 | Surface metal and nonmetal mines | 45 |
| 30 CFR 56.20003 | Surface metal and nonmetal mines | 35 |
| 30 CFR 56.4201 | Surface metal and nonmetal mines | 33 |
| 30 CFR 56.12004 | Surface metal and nonmetal mines | 31 |
| 30 CFR 56.12028 | Surface metal and nonmetal mines | 31 |
| 30 CFR 56.14132 | Surface metal and nonmetal mines | 25 |
| 30 CFR 56.14112 | Surface metal and nonmetal mines | 21 |
| 30 CFR 56.12032 | Surface metal and nonmetal mines | 20 |
| 30 CFR 56.12030 | Surface metal and nonmetal mines | 20 |
| 30 CFR 56.14207 | Surface metal and nonmetal mines | 15 |
| 30 CFR 56.11001 | Surface metal and nonmetal mines | 15 |
| 30 CFR 56.12008 | Surface metal and nonmetal mines | 14 |
| 30 CFR 56.12018 | Surface metal and nonmetal mines | 13 |
| 30 CFR 56.18002 | Surface metal and nonmetal mines | 13 |
Injury and illness cases at bentonite mines
Accident reports by degree of injury, as the operator reported them to MSHA.
| Degree | Cases |
|---|---|
| Days away from work or restricted activity | 92 |
| No lost time, or an occupational illness | 27 |
What the accident reports at bentonite mines describe
Accident classification, as MSHA codes the circumstances that contributed most directly.
| Classification | Reports |
|---|---|
| Slip or fall of person | 35 |
| Handling of materials | 29 |
| Powered haulage | 22 |
| Handtools (nonpowered) | 14 |
| Machinery | 7 |
| Other | 7 |
| Striking or bumping | 4 |
| Stepping or kneeling on object | 2 |
| Disorders (repeated trauma) | 1 |
| Exploding vessels under pressure | 1 |
Equipment named in accident reports at bentonite mines
| Equipment | Reports |
|---|---|
| Scraper loader | 17 |
| Hand tools (not powered) | 14 |
| Road grader | 5 |
| Bulldozer | 5 |
| Packaging machine | 3 |
| Front-end loader | 3 |
| Ore haulage trucks - off highway trucks | 2 |
| Mine car | 2 |
| Trucks | 2 |
| Conveyor | 2 |
Updated November 6, 2026. Read from US Department of Labor, Mine Safety and Health Administration (MSHA), Open Government Data Sets. US government work, public domain. Counts come from the MSHA files published on November 6, 2026. An open mine is one MSHA lists as Active, Intermittent, New Mine, Temporarily Idled or NonProducing; 13,673 were open that day. Citations, penalties, inspections and accident reports run from January 1, 2022. A citation is an inspector's allegation and an operator can contest it; the penalty is the amount MSHA first proposed, before any contest or settlement. An operator is the legal entity MSHA assesses, and a parent company is its controller. Mines run by sole proprietors or by individuals are counted in every total and are not named. This page uses MSHA data and is not endorsed or certified by MSHA. Free to reuse with credit to SpecStream under CC BY 4.0. Spot a wrong value? Write to [email protected] with the link to this page.