Twin Mountain Rock Venture · Accident type, without injuries
Slid off a sluff bank and turned over dozer. Material kept the dozer in almost like slow motion. No injury windows came out whole, and back one stayed in.
Twin Mountain Rock Metal/Non-Metal
Twin Mountain Rock Venture
· Surface
Controlled by
Eddie Antonini
Little Lake,
Inyo County,
CA
·
Active
MSHA Mine ID: 0403623
Twin Mountain Rock has $59K in proposed MSHA penalties and $3K outstanding across 2 contested dockets, plus health sampling and the full incident record.
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- Fatalities
- 0
- Total incidents
- 12
- Years on record
- 1989–2021
- Latest incident
- Jun 2021
Compliance record
MSHA citations since 2000
160
citations
40
significant & substantial
$59,294
proposed penalties
$48,227
paid to date
81% of proposed penalties paid to date, a $11,067 gap.
Source: MSHA violations data, updated weekly.
Inspection activity
MSHA inspections since 2000
77
inspections on record
1,176
inspection hours
13.6
citations per 100 inspection hours
ⓘ
This rate is recorded citations divided by MSHA inspection hours, per 100 hours. It reflects inspection effort, not mine size or production.160 citations across 1,176 inspection hours.
Source: MSHA inspections data, updated weekly.
Twin Mountain Rock has $59K in proposed MSHA penalties and $3K outstanding across 2 contested dockets.
Penalty disposition
ⓘ
Differences between proposed and paid penalties reflect both settlements and conference reductions and amounts still owed. Outstanding is the balance currently owed.$59K
proposed penalties
$51K
current assessed
$48K
paid to date
$3K
outstanding
159 assessments are final orders; 2 contested dockets.
As of the most recent assessment on 2026-02-11.
Source: MSHA assessed-violations and conference/litigation data, updated weekly.
See also
the operator's enforcement record
Quarterly safety rates
ⓘ
Citations per million reported employee-hours. Rates begin in 2000, when MSHA's quarterly employment data starts; earlier incidents are counted but cannot be rate-adjusted. Quarters under 100,000 reported hours are greyed: too few hours for a stable rate.Citations per million employee-hours, as reported to MSHA
| Quarter | Hours worked | Citations | S&S | Per 1M hrs |
|---|---|---|---|---|
| 2025 Q4 | 2,268 | 0 | 0 | 0.0 |
| 2025 Q3 | 1,999 | 0 | 0 | 0.0 |
| 2025 Q2 | 2,409 | 0 | 0 | 0.0 |
| 2025 Q1 | 1,796 | 1 | 0 | 556.8 |
| 2024 Q4 | 2,258 | 0 | 0 | 0.0 |
| 2024 Q3 | 1,954 | 9 | 1 | 4605.9 |
| 2024 Q2 | 2,411 | 0 | 0 | 0.0 |
| 2024 Q1 | 1,873 | 1 | 0 | 533.9 |
Show 96 earlier quarters Hide earlier quarters
| Quarter | Hours worked | Citations | S&S | Per 1M hrs |
|---|---|---|---|---|
| 2023 Q4 | 1,764 | 0 | 0 | 0.0 |
| 2023 Q3 | 1,874 | 0 | 0 | 0.0 |
| 2023 Q2 | 2,422 | 3 | 2 | 1238.6 |
| 2023 Q1 | 1,764 | 0 | 0 | 0.0 |
| 2022 Q4 | 2,245 | 3 | 0 | 1336.3 |
| 2022 Q3 | 2,052 | 2 | 0 | 974.7 |
| 2022 Q2 | 2,449 | 0 | 0 | 0.0 |
| 2022 Q1 | 2,298 | 0 | 0 | 0.0 |
| 2021 Q4 | 2,605 | 4 | 1 | 1535.5 |
| 2021 Q3 | 2,340 | 0 | 0 | 0.0 |
| 2021 Q2 | 2,523 | 2 | 2 | 792.7 |
| 2021 Q1 | 2,387 | 0 | 0 | 0.0 |
| 2020 Q4 | 2,711 | 0 | 0 | 0.0 |
| 2020 Q3 | 2,426 | 0 | 0 | 0.0 |
| 2020 Q2 | 2,115 | 4 | 0 | 1891.3 |
| 2020 Q1 | 2,123 | 0 | 0 | 0.0 |
| 2019 Q4 | 2,518 | 3 | 2 | 1191.4 |
| 2019 Q3 | 2,737 | 1 | 0 | 365.4 |
| 2019 Q2 | 2,839 | 0 | 0 | 0.0 |
| 2019 Q1 | 2,941 | 2 | 0 | 680.0 |
| 2018 Q4 | 2,371 | 0 | 0 | 0.0 |
| 2018 Q3 | 2,759 | 0 | 0 | 0.0 |
| 2018 Q2 | 2,626 | 1 | 0 | 380.8 |
| 2018 Q1 | 2,787 | 0 | 0 | 0.0 |
| 2017 Q4 | 2,184 | 2 | 0 | 915.8 |
| 2017 Q3 | 3,180 | 0 | 0 | 0.0 |
| 2017 Q2 | 2,826 | 1 | 1 | 353.9 |
| 2017 Q1 | 3,198 | 4 | 0 | 1250.8 |
| 2016 Q4 | 2,818 | 0 | 0 | 0.0 |
| 2016 Q3 | 3,457 | 0 | 0 | 0.0 |
| 2016 Q2 | 2,602 | 5 | 2 | 1921.6 |
| 2016 Q1 | 2,482 | 1 | 0 | 402.9 |
| 2015 Q4 | 3,180 | 0 | 0 | 0.0 |
| 2015 Q3 | 2,649 | 2 | 1 | 755.0 |
| 2015 Q2 | 827 | 4 | 0 | 4836.8 |
| 2015 Q1 | 3,819 | 0 | 0 | 0.0 |
| 2014 Q4 | 3,234 | 7 | 0 | 2164.5 |
| 2014 Q3 | 2,976 | 0 | 0 | 0.0 |
| 2014 Q2 | 1,662 | 4 | 1 | 2406.7 |
| 2014 Q1 | 2,160 | 0 | 0 | 0.0 |
| 2013 Q4 | 2,281 | 6 | 3 | 2630.4 |
| 2013 Q3 | 1,848 | 0 | 0 | 0.0 |
| 2013 Q2 | 2,092 | 2 | 0 | 956.0 |
| 2013 Q1 | 2,266 | 1 | 1 | 441.3 |
| 2012 Q4 | 2,380 | 0 | 0 | 0.0 |
| 2012 Q3 | 1,979 | 0 | 0 | 0.0 |
| 2012 Q2 | 1,778 | 0 | 0 | 0.0 |
| 2012 Q1 | 2,117 | 1 | 1 | 472.4 |
| 2011 Q4 | 3,171 | 0 | 0 | 0.0 |
| 2011 Q3 | 2,451 | 0 | 0 | 0.0 |
| 2011 Q2 | 2,603 | 2 | 1 | 768.3 |
| 2011 Q1 | 2,572 | 0 | 0 | 0.0 |
| 2010 Q4 | 3,412 | 4 | 2 | 1172.3 |
| 2010 Q3 | 2,468 | 0 | 0 | 0.0 |
| 2010 Q2 | 2,267 | 1 | 0 | 441.1 |
| 2010 Q1 | 2,156 | 0 | 0 | 0.0 |
| 2009 Q4 | 2,418 | 2 | 0 | 827.1 |
| 2009 Q3 | 2,092 | 0 | 0 | 0.0 |
| 2009 Q2 | 2,291 | 0 | 0 | 0.0 |
| 2009 Q1 | 2,097 | 1 | 0 | 476.9 |
| 2008 Q4 | 2,545 | 9 | 3 | 3536.3 |
| 2008 Q3 | 2,819 | 2 | 2 | 709.5 |
| 2008 Q2 | 2,751 | 5 | 0 | 1817.5 |
| 2008 Q1 | 2,903 | 0 | 0 | 0.0 |
| 2007 Q4 | 3,281 | 5 | 2 | 1523.9 |
| 2007 Q3 | 4,291 | 0 | 0 | 0.0 |
| 2007 Q2 | 6,682 | 1 | 0 | 149.7 |
| 2007 Q1 | 4,855 | 0 | 0 | 0.0 |
| 2006 Q4 | 5,563 | 5 | 1 | 898.8 |
| 2006 Q3 | 4,682 | 6 | 1 | 1281.5 |
| 2006 Q2 | 4,657 | 8 | 2 | 1717.8 |
| 2006 Q1 | 5,744 | 14 | 0 | 2437.3 |
| 2005 Q4 | 4,287 | 0 | 0 | 0.0 |
| 2005 Q3 | 4,658 | 0 | 0 | 0.0 |
| 2005 Q2 | 4,898 | 0 | 0 | 0.0 |
| 2005 Q1 | 4,908 | 0 | 0 | 0.0 |
| 2004 Q4 | 4,272 | 0 | 0 | 0.0 |
| 2004 Q3 | 4,597 | 0 | 0 | 0.0 |
| 2004 Q2 | 4,521 | 0 | 0 | 0.0 |
| 2004 Q1 | 4,672 | 4 | 2 | 856.2 |
| 2003 Q4 | 4,457 | 0 | 0 | 0.0 |
| 2003 Q3 | 4,702 | 0 | 0 | 0.0 |
| 2003 Q2 | 4,988 | 2 | 2 | 401.0 |
| 2003 Q1 | 4,455 | 0 | 0 | 0.0 |
| 2002 Q4 | 4,377 | 1 | 1 | 228.5 |
| 2002 Q3 | 4,947 | 0 | 0 | 0.0 |
| 2002 Q2 | 4,922 | 2 | 0 | 406.3 |
| 2002 Q1 | 4,754 | 0 | 0 | 0.0 |
| 2001 Q4 | 4,386 | 0 | 0 | 0.0 |
| 2001 Q3 | 3,905 | 2 | 1 | 512.2 |
| 2001 Q2 | 4,119 | 0 | 0 | 0.0 |
| 2001 Q1 | 3,690 | 0 | 0 | 0.0 |
| 2000 Q4 | 3,521 | 0 | 0 | 0.0 |
| 2000 Q3 | 3,980 | 7 | 2 | 1758.8 |
| 2000 Q2 | 3,714 | 0 | 0 | 0.0 |
| 2000 Q1 | 4,582 | 0 | 0 | 0.0 |
No fatalities recorded at this mine.
Reportable incidents
12 on file2021 · 1 incident
2015 · 1 incident
June 4, 2015
CA · Metal/Non-Metal
laborer, blacksmith, bull gang, parts runner, roustabout, pick-up man, pitman
HANDLING OF MATERIALS
Twin Mountain Rock Venture · Caught in, under or between (Not Elsewhere Classified)
While working on #27 conveyor employees hand got caught in between the stand holding the conveyor and the conveyor. Machine being used to hold conveyor bled off pinching employees left hand below pinkie finger.
2013 · 1 incident
January 15, 2013
CA · Metal/Non-Metal
warehouseman, bagger, palletizer/stacker, store keeper, packager, fabricator, cleaning plant operator
MACHINERY
Cemex Construction Materials LP · Struck by... (Not Elsewhere Classified)
Hose came loose from air wrench and struck employee above the left eye, lacerating the scalp and knocking off his safety glasses.
2008 · 1 incident
June 23, 2008
CA · Metal/Non-Metal
warehouseman, bagger, palletizer/stacker, store keeper, packager, fabricator, cleaning plant operator
HANDLING OF MATERIALS
Rinker Materials Western Inc · Struck against stationary object
Worker cut finger while working on D8N dozer. Required seven stitches. Returned to work same day limited duty.
2007 · 1 incident
Rinker Materials Western Inc · Struck by... (Not Elsewhere Classified)
Employee was working on shaker screen. He had lifted and secured a discharge lip on the top deck of the screen so that he could work on the second deck of the screen. After climbing into begin work on the screen a gust of wind caused the discharge lip above him to fall. The lip struck the employee on the back and caused him to hit his chest on the deck in front of him.
2006 · 1 incident
May 22, 2006
CA · Metal/Non-Metal
beltman, conveyor man, conveyor belt worker, mobile bridge carrierman, feeder operator, conveyor rider
SLIP OR FALL OF PERSON
Rinker Materials Western Inc · Fall to the walkway or working surface
Employee was running to turn off conveyor belt when he slipped and fell. The employee received a lower back strain from the fall.
1994 · 2 incidents
March 28, 1994
CA · Metal/Non-Metal
maintenance man, mechanic, repair/serviceman, boilermaker, fueler, tire tech, field service tech
SLIP OR FALL OF PERSON
Twin Mountain Rock Company · Fall to lower level, (Not Elsewhere Classified)
EMPLOYEE WAS WELDING OVER HEAD STANDING SEMI-SUSPENDED IN THE FRAME WORK OF THE 3RD DECK OF THE 2X20 WITH HIS FEET ON THE SKIRTBOARD BELOW. THE ROD HE WAS USING EXPLODED. A PIECE OF HOT FLUX L ANDED CLOSE TO THE CORNER OF HIS LEFT EYE, UNDER HIS HOOD. IN THE SCRAMBLE TO REMOVE HOT FLUX, HE SLIPPED THROUGH THE FRAME AND HIT IS BACK. HOT FLUX WAS REPORTED THEN, NOT THE FALL TIL 4-4-9
March 7, 1994
CA · Metal/Non-Metal
front-end loader, scraper-loader operator, pan operator, payloader, scraper rig operator
HANDLING OF MATERIALS
Twin Mountain Rock Company · Struck by flying object
EMPLOYEE WAS PREPARING TO SHUT DOWN PLANT, GOT OUT OF LOADER, AND WALKED DOWN THROUGH THE PLANT. WIND WAS BLOWING. EMPLOYEE GOT CINDERS IN HIS LEFT EYE. HE APPARENTLY RUBBED IT. IT BECAME IMBE DDED. HE WAS WEARING SAFETY GLASSES. DOCTOR REMOVED PARTICLE.
1990 · 1 incident
September 25, 1990
CA · Metal/Non-Metal
greaser, grease man, oiler, lube man, dragline oiler
HANDLING OF MATERIALS
Twin Mountain Rock Company · Struck by... (Not Elsewhere Classified)
EMPLOYEE WAS REPLACING A TAIL PULLEY GUARD ON A CONVEYOR BELT. THE GUARD SLIPPED AND A SHARP EDGE CUT THE FIRST FINGER ON HIS RIGHT HAND, REQUIRING FIVE STITCHES.
1989 · 3 incidents
August 16, 1989
CA · Metal/Non-Metal
haul/off road/coal/ore/pit/quarry/rock/rubber tire truck driver, transportation truck driver
HANDTOOLS (NONPOWERED)
Twin Mountain Rock Company · Struck against stationary object
HIT HIS HAND ON A PIECE OF METAL WHEN HIS WRENCH SLIPPED OFF BOLT HEAD.
Twin Mountain Rock Company · Caught in, under or between (Not Elsewhere Classified)
EMPLOYEE WAS REMOVING CONE CRUSHER LINING WHEN HIS MIDDLE FINGER GOT CAUGHT ON OUTSIDE EDGE OF CONE CRUSHER AND TORE HIS MIDDLE FINGER NAIL OFF.
April 17, 1989
CA · Metal/Non-Metal
laborer, blacksmith, bull gang, parts runner, roustabout, pick-up man, pitman
SLIP OR FALL OF PERSON
Twin Mountain Rock Company · Fall from machine
SLIPPED ON STEP WHILE GETTING OUT OF TRUCK-HIT ELBOW ON STEPS AS HE FELL. SUFFERED BRUISES AND SWELLING.
For insurers, brokers, and safety consultants
The full compliance file on Twin Mountain Rock
A dated report covering the 26-year penalty trail, line-item violation pattern, contest and docket posture, rate-normalized peer benchmark, and full fatality history. Delivered as a PDF with the underlying data as CSV.