MINE DETAILS
Rockfield Plant
MSHA MINE ID0401897
LOCATION
Mine location
1 of 1 mine with usable MSHA coordinates. Select a marker to open a mine.
Mine coordinates
- Rockfield Plant36.93083, -119.73528Open map ↗
Quarterly trends
2025 Q1 – 2026 Q4
Database snapshot · 2026-10-13. MSHA quarterly production and employment reports.
Coal production
0reported short tons
Hours worked
79,701reported employee hours
Tons per hour
0.00production ÷ hours worked
Missing values appear as —. Totals use available reports. Tons per hour requires production and hours for the same quarters and a nonzero hours total. * Striped bars mark partial mine coverage or an incomplete quarter. See the table for coverage.
Quarterly data and reporting coverage
| Quarter | Coal (short tons) | Hours worked | Tons / hour | Avg. employees | Coverage |
|---|---|---|---|---|---|
| 2025 Q1 | 0 | 14,466 | 0.00 | 21 | 1/1 mines reporting |
| 2025 Q2 | 0 | 14,036 | 0.00 | 21 | 1/1 mines reporting |
| 2025 Q3 | 0 | 14,294 | 0.00 | 22 | 1/1 mines reporting |
| 2025 Q4 | 0 | 13,200 | 0.00 | 20 | 1/1 mines reporting |
| 2026 Q1 | 0 | 12,889 | 0.00 | 20 | 1/1 mines reporting |
| 2026 Q2 | 0 | 10,816 | 0.00 | 20 | 1/1 mines reporting |
| 2026 Q3 | — | — | — | — | No report |
| 2026 Q4 | — | — | — | — | No report |
Safety and enforcement
2025-01-01 – 2026-10-13
Violations
121 significant & substantial (S&S)
Accident records
00 records classified as fatality
Proposed penalties · USD
3,418.0012 of 12 violations with amounts
On-site inspection hours
74.757 inspections · 7 with hours
Counts are published records, including contractor records. * The quarter was incomplete at the snapshot date; recent counts may rise as reports arrive. — means no reported amount or hours. Portfolio totals use current membership.
Quarterly safety data
| Quarter | Violations | S&S | Proposed USD | Accident records | Fatality records | Inspections | On-site hours |
|---|---|---|---|---|---|---|---|
| 2025-Q1 | 2 | 0 | 302.00 | 0 | 0 | 1 | 12.3 |
| 2025-Q2 | 2 | 0 | 360.00 | 0 | 0 | 1 | 6.3 |
| 2025-Q3 | 2 | 0 | 848.00 | 0 | 0 | 1 | 12.3 |
| 2025-Q4 | 0 | 0 | — | 0 | 0 | 1 | 17.8 |
| 2026-Q1 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2026-Q2 | 6 | 1 | 1,908.00 | 0 | 0 | 3 | 26.3 |
| 2026-Q3 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2026-Q4 * | 0 | 0 | — | 0 | 0 | 0 | — |
Most cited CFR sections
All violations issued in the selected period. Counts combine subsections.
Safety activity
Compliance Follow-up Inspection · 8.5 on-site hours
Compliance Follow-up Inspection · 1.0 on-site hours
62.130(a) · $151.00 proposed
56.14100(c) · $209.00 proposed
56.11002 · $151.00 proposed
56.11027 · $209.00 proposed
56.11001 · S&S · $1,037.00 proposed
56.14107(a) · $151.00 proposed
Regular Safety and Health Inspection · 16.8 on-site hours
Regular Safety and Health Inspection · 17.8 on-site hours
62.130(a) · $697.00 proposed
50.30(a) · $151.00 proposed
Spot Inspection · 12.3 on-site hours
56.20003(a) · $209.00 proposed
56.14100(b) · $151.00 proposed
Regular Safety and Health Inspection · 6.3 on-site hours
56.12032 · $151.00 proposed
56.12018 · $151.00 proposed
Regular Safety and Health Inspection · 12.3 on-site hours
Safety sources and definitions
MSHA Violations (issue date), Accidents (accident date), and Inspections (begin date). Snapshot 2026-10-13.
Counts describe published rows, including contractor records; accident records are not distinct incidents or numbers of people injured.
Zero means no matching records in the imported sources, not proof of no events. Historical coverage differs by source; absence before a source begins reporting is not a zero incident rate. Invalid or absent dates and records after the snapshot are excluded.
S&S means SIG_SUB=Y. Fatality records use DEGREE_INJURY_CD=01. Proposed penalties are not final assessed or paid amounts; missing dollar values are omitted.
Inspection hours are SUM_TOTAL_ON_SITE_HOURS attributed to the inspection start date, without supervisor/trainee hours. Missing hours are omitted; a started inspection may still be open.
Portfolio totals use current mine membership, including events before the current owner or operator's tenure.
CFR headings link to the current Title 30 index; they are not historical legal determinations.
OWNERSHIP
Operator and controller history
Current ownership comes from MSHA Mines. Historical start and end dates come from MSHA Controller and Operator History.
—
Cemex S AcontrolsCEMEX Construction Materials Pacific, LLCoperatesRockfield Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 0401897—
Cemex S AcontrolsCemex Construction Materials LPoperatesRockfield Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 0401897—
Cemex S AcontrolsCEMEXoperatesRockfield Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 0401897—
RMC Group PLCcontrolsCEMEXoperatesRockfield Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 0401897—
Lone Star Industries InccontrolsLone Star Industries IncoperatesRockfield Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 0401897Other historical summaries · source-specific periods
RECORD SUMMARY
Production, safety and enforcement
These summaries use the periods stated on each card, independently of the reporting period above.
01 / SAFETYwatch
Accidents and injuries
5 historical accident/injury rows; 0 coded fatalities and 572 lost days across the published record.
ACCIDENT + INJURY RECORD2 since 2021
accidentsmine-production-quarterly02 / COMPLIANCEwatch
Violations and penalties
219 violation rows across the full record; 61 carry an S&S flag and $50,424 appears in current assessed amounts.
ENFORCEMENT ACTIVITY33 since 2021
inspectionsviolationsassessed-violationsorders-107a03 / HEALTHwatch
Occupational health samples
19 personal. 1 personal-sample rows have a published C/E ratio above 1; 0 noise rows have an action-level or PEL dose above 100%. These are separate measures, not a silica exceedance count. Silica results and sample status are shown separately.
OCCUPATIONAL EXPOSURE19 samples
personal-health-samples04 / PRODUCTIONcontext
Quarterly production and employment
11K employee hours and 20 summed average employees across reported subunits in the latest published quarter.
2026-Q20 tons
mine-production-quarterlymine-production-yearly05 / LEGALwatch
Contests, conferences and decisions
5 contested-violation rows, 5 civil-penalty docket/decision rows, and 10 conference records linked by issuance number.
POST-ISSUANCE LIFECYCLE20 linked rows
conferencescontested-violationscivil-penalty-dockets-decisions06 / CONTRACTORScontext
Contractors
Contractors are linked through this mine’s violation or accident records. Their production and hours cover all their operations, so they are not included in this mine’s totals.
ENTITY-LEVEL CONTEXT7 linked entities
contractor-production-quarterlycontractor-production-yearlyaccidentsviolations07 / INSPECTIONScontext
Inspections
82 inspection events and 2K published inspection hours across the historical record.
OVERSIGHT COVERAGE17 since 2021
inspectionsviolationsHEALTH SAMPLING
Silica and quartz
Coal quartz, metal/nonmetal personal samples and area samples. Snapshot Oct 13, 2026. 10 silica records across the mine’s published history.
Personal silica samples · concentration / limit
Quarterly mean · published C/E ratio
— No eligible measurements. * Quarter in progress. Means describe the available samples, not average exposure across the mine.
Quartz % is the sample’s quartz content; µg/m³ is its reported concentration. Personal C/E is the ratio to the limit published with that sample. Personal and area concentration units and void status are not specified in those source files.
| Date / sample | Dataset / analyte | Occupation / area | Measurement | Sample status | Published action |
|---|---|---|---|---|---|
| 000000202601834600 | Metal/nonmetal personalQuartz, respirable, >1% Qtz | Dry Screen Plant Operator | 0.18× published limitConcentration: 0000.14 · limit: 0000.80Source unit unspecified | Not reported | NO ACTIONInspection F034D59 |
Sources and interpretation
- Coal means use numeric concentrations from samples marked not voided, excluding control/invalid sample types and dates after the snapshot. Missing values remain null; reported zeroes remain zero.
- Quarterly means describe available samples, not mine-wide or worker-average exposure. Quarters with no eligible measurements remain empty; the current quarter is partial.
- Personal C/E is MSHA's published concentration-to-limit ratio. A value above 1 is not by itself a citation or a determination under the 2024 silica rule. Personal and area files do not publish a void-status field.
- Area records include bulk-dust analyses and are kept separate from personal exposure results. Their concentration units are not specified in the source dictionary.
- Missing samples do not establish safe conditions. Coal quartz percentage and concentration are separate measures. No compliance threshold is inferred for coal samples.
Coal quartz field definitions ↗Metal/nonmetal personal field definitions ↗Metal/nonmetal area field definitions ↗
EIA + TITLE 30
EIA production and cited regulations
EIA annual figures are reported separately from MSHA. Regulation links use the current eCFR snapshot.
Not present in the 2024 EIA coal workbook.
This can mean the operation is non-coal, inactive for the annual period, or outside the EIA-7A reporting population.
30 CFR 62.130Permissible exposure level.2 recent rows ↗30 CFR 56.14100Safety defects; examination, correction and records.2 recent rows ↗30 CFR 56.11002Handrails and toeboards.1 recent row ↗30 CFR 56.11027Scaffolds and working platforms.1 recent row ↗30 CFR 56.11001Safe access.1 recent row ↗30 CFR 56.14107Moving machine parts.1 recent row ↗30 CFR 50.30Preparation and submission of MSHA Form 7000-2—Quarterly Employment and Coal Production Report.1 recent row ↗30 CFR 56.20003Housekeeping.1 recent row ↗
RECENT PUBLIC RECORDS
Recent violations and samples
Latest records retained for inspection; aggregates above use the full source history.
516241862.130(a)Citation
516241756.14100(c)Citation
516241656.11002Citation
516241556.11027Citation
516241456.11001S&S
516241356.14107(a)Citation
510291862.130(a)Citation
510291750.30(a)Citation
Coal dust, noise and other contaminants. Silica records above ↑
Respirable dust, <.1mgWasher Operator
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgCrusher Oper/Worker
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgScreen/Scalper Operator
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgFront-end Loader Operator
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
Respirable dust, <.1mgLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0000.00Source unit unspecified
SOURCE COVERAGE
Reporting dates and coverage
15 datasets contain linked records. Missing datasets are listed below.
DATASETROWSWINDOWSTATUS
Accident, Injuries, and Illnessessafety · contractors5Feb 13, 2009—Aug 15, 2024mine-keyed
Addresses of Recordidentity · logistics1Feb 21, 1989—Feb 21, 1989mine-keyed
Assessed Violationscompliance · legal216Apr 11, 2000—Apr 29, 2026mine-keyed
Civil Penalty Dockets and Decisionscompliance · legal5Apr 27, 2011—Aug 6, 2014mine-keyed
Coal Dust Sampleshealth · safety—No published rowsabsent / not applicable
Conferencescompliance · legal10Dec 6, 2002—Nov 1, 2013mine-keyed
Contested Violationscompliance · legal5Oct 21, 2009—Sep 5, 2013mine-keyed
Contractor Employment and Production — Quarterlycontractors · production · safety353Not published—Not publishedentity-linked
Contractor Employment and Production — Yearlycontractors · production · safety72Not published—Not publishedentity-linked
Controller and Operator Historyidentity · compliance5Jan 1, 1950—Apr 20, 2012mine-keyed
Mine Employment and Production — Quarterlyproduction · safety · compliance212Not published—Not publishedmine-keyed
Mine Employment and Production — Yearlyproduction · safety · compliance54Not published—Not publishedmine-keyed
Inspectionssafety · compliance82Apr 11, 2000—Jun 22, 2026mine-keyed
Minesidentity · production · logistics1Not published—Not publishedmine-keyed
Metal and Nonmetal Area Sampleshealth · safety—No published rowsabsent / not applicable
Metal and Nonmetal Personal Health Sampleshealth · safety19Jul 10, 2002—Apr 29, 2026mine-keyed
Noise Sampleshealth · safety · equipment—No published rowsabsent / not applicable
Quartz Samples — Coalhealth · safety—No published rowsabsent / not applicable
Violationscompliance · safety · legal219Apr 11, 2000—Apr 29, 2026mine-keyed
107(a) Orders Issuedsafety · compliance—No published rowsabsent / not applicable
NOTES
Limitations
- Contractor production is entity-level and is never represented as mine-attributable.
- Missing rows can mean no event, publication delay, identity mismatch, or inapplicability.