MINE DETAILS
Mason City Plant
MSHA MINE ID1300095
LOCATION
Mine location
1 of 1 mine with usable MSHA coordinates. Select a marker to open a mine.
Mine coordinates
- Mason City Plant43.17750, -93.21417Open 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
439,649reported 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 | 69,229 | 0.00 | 119 | 1/1 mines reporting |
| 2025 Q2 | 0 | 74,530 | 0.00 | 127 | 1/1 mines reporting |
| 2025 Q3 | 0 | 75,235 | 0.00 | 130 | 1/1 mines reporting |
| 2025 Q4 | 0 | 70,376 | 0.00 | 130 | 1/1 mines reporting |
| 2026 Q1 | 0 | 74,502 | 0.00 | 128 | 1/1 mines reporting |
| 2026 Q2 | 0 | 75,777 | 0.00 | 130 | 1/1 mines reporting |
| 2026 Q3 | — | — | — | — | No report |
| 2026 Q4 | — | — | — | — | No report |
Safety and enforcement
2025-01-01 – 2026-10-13
Violations
26748 significant & substantial (S&S)
Accident records
70 records classified as fatality
Proposed penalties · USD
859,349.00266 of 267 violations with amounts
On-site inspection hours
486.5018 inspections · 18 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 | 23 | 3 | 32,976.00 | 1 | 0 | 5 | 12.3 |
| 2025-Q2 | 65 | 8 | 138,795.00 | 1 | 0 | 1 | 105.5 |
| 2025-Q3 | 0 | 0 | — | 0 | 0 | 0 | — |
| 2025-Q4 | 0 | 0 | — | 1 | 0 | 0 | — |
| 2026-Q1 | 62 | 7 | 206,707.00 | 2 | 0 | 6 | 123.5 |
| 2026-Q2 | 1 | 0 | 151.00 | 0 | 0 | 4 | 26.5 |
| 2026-Q3 | 116 | 30 | 480,720.00 | 2 | 0 | 2 | 218.8 |
| 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 · 0.0 on-site hours
50.20(b)
56.5001(a)/56.5005 · $1,219.00 proposed
56.5001(a)/56.5005 · $1,219.00 proposed
56.20003(a) · $2,133.00 proposed
56.4201(a)(1) · $1,219.00 proposed
56.20003(a) · S&S · $2,133.00 proposed
56.20003(a) · S&S · $2,133.00 proposed
56.20003(a) · S&S · $2,133.00 proposed
56.20003(a) · S&S · $2,133.00 proposed
56.14112(b) · $313.00 proposed
56.20003(a) · S&S · $15,768.00 proposed
56.14100(b) · $432.00 proposed
56.14130(g) · $151.00 proposed
56.14205 · $151.00 proposed
56.4601 · $432.00 proposed
56.14100(b) · $193.00 proposed
56.20003(a) · $549.00 proposed
56.12032 · $432.00 proposed
56.14112(a)(1) · $288.00 proposed
56.14112(a)(1) · S&S · $959.00 proposed
56.20003(a) · S&S · $20,047.00 proposed
56.20003(a) · S&S · $20,047.00 proposed
56.14112(a)(1) · $432.00 proposed
56.20003(a) · S&S · $20,047.00 proposed
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.
—
Heidelberg Materials AGcontrolsHeidelberg Materials US Cement LLCoperatesMason City Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 1300095—
Heidelberg Materials AGcontrolsLehigh Portland Cement CompanyoperatesMason City Plant
msha-controller-operator-history · controller/operator co-tenure derived on mine 1300095Other 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
232 historical accident/injury rows; 0 coded fatalities and 2,710 lost days across the published record.
ACCIDENT + INJURY RECORD16 since 2021
accidentsmine-production-quarterly02 / COMPLIANCEwatch
Violations and penalties
2,480 violation rows across the full record; 551 carry an S&S flag and $3,299,629 appears in current assessed amounts.
ENFORCEMENT ACTIVITY675 since 2021
inspectionsviolationsassessed-violationsorders-107a03 / HEALTHwatch
Occupational health samples
130 personal; 37 area. 8 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 EXPOSURE167 samples
personal-health-samplesarea-samples04 / PRODUCTIONcontext
Quarterly production and employment
76K employee hours and 130 summed average employees across reported subunits in the latest published quarter.
2026-Q20 tons
mine-production-quarterlymine-production-yearly05 / LEGALwatch
Contests, conferences and decisions
470 contested-violation rows, 527 civil-penalty docket/decision rows, and 113 conference records linked by issuance number.
POST-ISSUANCE LIFECYCLE1,110 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 CONTEXT53 linked entities
contractor-production-quarterlycontractor-production-yearlyaccidentsviolations07 / INSPECTIONScontext
Inspections
220 inspection events and 11K published inspection hours across the historical record.
OVERSIGHT COVERAGE52 since 2021
inspectionsviolationsHEALTH SAMPLING
Silica and quartz
Coal quartz, metal/nonmetal personal samples and area samples. Snapshot Oct 13, 2026. 14 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 |
|---|---|---|---|---|---|
| 000000202603485174 | Metal/nonmetal areaQUARTZ (BULK DUST) | MP GRINDING | C/E not reportedConcentration: 0000.0000Source unit unspecified | Not reported | NO ACTIONInspection F02A784 |
| 000000202603485074 | Metal/nonmetal areaQUARTZ (BULK DUST) | MP DRYING/ROAST | C/E not reportedConcentration: 0000.0000Source unit unspecified | Not reported | NO ACTIONInspection F02A784 |
| 000000202603485274 | Metal/nonmetal areaQUARTZ (BULK DUST) | MP GRINDING | C/E not reportedConcentration: 0000.0000Source unit unspecified | Not reported | NO ACTIONInspection F02A784 |
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 50.20Preparation and submission of MSHA Report Form 7000-1—Mine Accident, Injury, and Illness Report.1 recent row ↗30 CFR 56.5001Exposure limits for airborne contaminants.2 recent rows ↗30 CFR 56.20003Housekeeping.6 recent rows ↗30 CFR 56.4201Inspection.1 recent row ↗30 CFR 56.14112Construction and maintenance of guards.1 recent row ↗30 CFR 56.14100Safety defects; examination, correction and records.1 recent row ↗
RECENT PUBLIC RECORDS
Recent violations and samples
Latest records retained for inspection; aggregates above use the full source history.
511479250.20(b)Citation
522076956.5001(a)/56.5005Citation
522076856.5001(a)/56.5005Citation
976336956.20003(a)Citation
522075956.4201(a)(1)Citation
522075856.20003(a)S&S
522075756.20003(a)S&S
522075656.20003(a)S&S
Coal dust, noise and other contaminants. Silica records above ↑
Nuisance dust, total, <1% QtzBall Mill Operator
C/E: 00.57Concentration: 0005.72 · limit: 0010.00Source unit unspecified
Nuisance dust, total, <1% QtzCleanup Man
C/E: 00.32Concentration: 0003.22 · limit: 0010.00Source unit unspecified
Nuisance dust, total, <1% QtzLaborer, Bullgang
C/E: 00.59Concentration: 0005.93 · limit: 0010.00Source unit unspecified
Nuisance dust, total, <1% QtzSupervisor, Co. Official
C/E: 00.86Concentration: 0008.62 · limit: 0010.00Source unit unspecified
Nuisance dust, total, <1% QtzLaborer, Bullgang
C/E: 01.22Concentration: 0012.24 · limit: 0010.00Source unit unspecified
Nuisance dust, total, <1% QtzBall Mill Operator
C/E: 01.50Concentration: 0014.97 · limit: 0010.00Source unit unspecified
Molybdenum dustLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0010.00Source unit unspecified
Beryllium dustLaborer, Bullgang
C/E: 00.00Concentration: 0000.00 · limit: 0002.00Source unit unspecified
SOURCE COVERAGE
Reporting dates and coverage
16 datasets contain linked records. Missing datasets are listed below.
DATASETROWSWINDOWSTATUS
Accident, Injuries, and Illnessessafety · contractors232Jan 25, 2000—Jul 26, 2026mine-keyed
Addresses of Recordidentity · logistics1May 15, 1974—May 15, 1974mine-keyed
Assessed Violationscompliance · legal2,470Feb 1, 2000—Sep 4, 2026mine-keyed
Civil Penalty Dockets and Decisionscompliance · legal527Jun 21, 2001—Jul 29, 2026mine-keyed
Coal Dust Sampleshealth · safety—No published rowsabsent / not applicable
Conferencescompliance · legal113Mar 28, 2000—Aug 22, 2022mine-keyed
Contested Violationscompliance · legal470Sep 6, 2005—Aug 6, 2026mine-keyed
Contractor Employment and Production — Quarterlycontractors · production · safety5,423Not published—Not publishedentity-linked
Contractor Employment and Production — Yearlycontractors · production · safety1,092Not published—Not publishedentity-linked
Controller and Operator Historyidentity · compliance2Jan 1, 1950—Feb 1, 2002mine-keyed
Mine Employment and Production — Quarterlyproduction · safety · compliance318Not published—Not publishedmine-keyed
Mine Employment and Production — Yearlyproduction · safety · compliance81Not published—Not publishedmine-keyed
Inspectionssafety · compliance220Feb 1, 2000—Sep 28, 2026mine-keyed
Minesidentity · production · logistics1Not published—Not publishedmine-keyed
Metal and Nonmetal Area Sampleshealth · safety37Jun 20, 2007—Aug 26, 2026mine-keyed
Metal and Nonmetal Personal Health Sampleshealth · safety130Feb 18, 2004—Sep 30, 2026mine-keyed
Noise Sampleshealth · safety · equipment—No published rowsabsent / not applicable
Quartz Samples — Coalhealth · safety—No published rowsabsent / not applicable
Violationscompliance · safety · legal2,480Feb 1, 2000—Sep 28, 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.