| — | M&R Contracting | CB1215 | Mine contractor | — |
| — | M&S Fabrication llc | CC2269 | Mine contractor | — |
| — | M&S Heavy Equiment Service, Inc. | CM717 | Mine contractor | — |
| — | M&S WELDING AND GENERAL CONTRACTING INC | CC8641 | Mine contractor | — |
| — | M&T enterprises | CC7071 | Mine contractor | — |
| — | M. A. R. S. | CJ740 | Mine contractor | — |
| — | M. B. Haynes Corporation | CZAT | Mine contractor | — |
| — | M. J. Electric, LLC | CAJ3 | Mine contractor | — |
| — | M. J. Price Construction Company, Inc. | CL863 | Mine contractor | — |
| — | M.C. Hall | CC6652 | Mine contractor | — |
| — | M.C. TRUCKING | CD941 | Mine contractor | — |
| — | M.C. Welding LLC | CC5163 | Mine contractor | — |
| — | M.D. Crushing and Excavating LLC | CC9826 | Mine contractor | — |
| — | M.Kline Trucking LLC | CC9039 | Mine contractor | — |
| — | M.P. BAKER ELECTRIC INC. | CF838 | Mine contractor | — |
| — | M2 welding | CC4530 | Mine contractor | — |
| — | M3 Engineering & Const Corp | CKIG | Mine contractor | — |
| — | M3 Explo | CC0441 | Mine contractor | — |
| — | Macallister Machinery | CKQU | Mine contractor | — |
| — | Macemore, Inc. | CJ605 | Mine contractor | — |
| — | Machine Diagnostics | CC0781 | Mine contractor | — |
| — | Machine Diagnostics, Inc. | CL761 | Mine contractor | — |
| — | Machine Reliability Management, Inc. | CA2211 | Mine contractor | — |
| — | MachineLife Ltd. | CC0008 | Mine contractor | — |
| — | Machinery Service Inc. | CZ631 | Mine contractor | — |
| — | Machinery Services Corp | CM0G | Mine contractor | — |
| — | MacKnight Safety Solutions, LLC | CC4834 | Mine contractor | — |
| — | MacLean Equipment USA Inc | CC1444 | Mine contractor | — |
| — | Macon Wire | C4ZT | Mine contractor | — |
| — | Mader Corporation | CB8219 | Mine contractor | — |
| — | Madsen Construction, INC | CC2866 | Mine contractor | — |
| — | Maga Trucking | CNLP | Mine contractor | — |
| — | Magia & Company, Inc. | CB7047 | Mine contractor | — |
| — | Magneco-Metrel, Inc. | CH786 | Mine contractor | — |
| — | Magnolia Surveying, LLC | CC9153 | Mine contractor | — |
| — | Magotteaux Inc | CYXY | Mine contractor | — |
| — | Maher Oil Company | CA0353 | Mine contractor | — |
| — | Main Electric Ltd | CEPN | Mine contractor | — |
| — | Maine Drilling & Blasting | CRI5 | Mine contractor | — |
| — | Maine Drilling & Blasting - Mid-Atlantic | CB5222 | Mine contractor | — |
| — | Maine Drilling & Blasting - New England Quarry S | CB5223 | Mine contractor | — |
| — | Maine Drilling & Blasting - Western Quarry | CB5224 | Mine contractor | — |
| — | Maintenance & Reliability Technologies, Inc. | CS728 | Mine contractor | — |
| — | Maintenance Service And Repair INC. | CC5411 | Mine contractor | — |
| — | Maintenance Solutions LLC | CA8736 | Mine contractor | — |
| — | Majestic Peak Solutions LLC. | CC3416 | Mine contractor | — |
| — | Major Asbestos Control Inc | CB061 | Mine contractor | — |
| — | Major Drilling America | CK921 | Mine contractor | — |
| — | Mako Metal Worx | CC1957 | Mine contractor | — |
| — | Malcom McCoy dba McCoy Trucking | CZ976 | Mine contractor | — |
| — | Malloy Electric & Bearing Supl | CI5M | Mine contractor | — |
| — | Malone Electric Co., Inc. | CA1127 | Mine contractor | — |
| — | Mammoet USA | C3MJ | Mine contractor | — |
| — | Mandros Painting Inc | CJL5 | Mine contractor | — |
| — | Manley Heavy Equipment Repair | CC8942 | Mine contractor | — |
| — | Mann Construction Company | CC8854 | Mine contractor | — |
| — | Manpower | CJ600 | Mine contractor | — |
| — | Manpower | CP229 | Mine contractor | — |
| — | Mansfield Sand & Select Llc. | CC4179 | Mine contractor | — |
| — | Mantenimiento Predictivo Computarizado | CC7823 | Mine contractor | — |
| — | Manuel Flores Conrete Construction | CW834 | Mine contractor | — |
| — | Manufacturers Equipment Co (MECO) | CB1638 | Mine contractor | — |
| — | Marathon Petroleum Company | CDCC | Mine contractor | — |
| — | Marathon Welding LLC | CC4141 | Mine contractor | — |
| — | Marcelo's LP | CB9782 | Mine contractor | — |
| — | Marco Crane | CMWX | Mine contractor | — |
| — | Mardian Equipment Co | CW231 | Mine contractor | — |
| — | Marfork Coal Company - Marfork Environmental | CS463 | Mine contractor | — |
| — | Maria Trucking Co., Inc | CFXA | Mine contractor | — |
| — | Marietta Silos, LLC | CL6X | Mine contractor | — |
| — | Mario Sinacola & Sons Excavating, Inc. | CJ348 | Mine contractor | — |
| — | Marion Docks, Inc. | CU413 | Mine contractor | — |
| — | Marion Environmental Inc | CZIM | Mine contractor | — |
| — | Mark Ann Industries Inc | CKW1 | Mine contractor | — |
| — | Mark Burke Builders | CA0916 | Mine contractor | — |
| — | Mark Haynes Construction Inc | CB7598 | Mine contractor | — |
| — | Mark Kilkenny Health/Safety Consultant | C7ZI | Mine contractor | — |
| — | Mark Young Trucking | CR781 | Mine contractor | — |
| — | Mark's Excavating & Trucking | CA4724 | Mine contractor | — |
| — | Markowski Excavating Inc | CBXC | Mine contractor | — |
| — | Marrone Trucking Inc | CJ435 | Mine contractor | — |
| — | Marschall Fire and Safety | CN808 | Mine contractor | — |
| — | Marsh & Legge Land Surveyors, P.L.C. | CV710 | Mine contractor | — |
| — | Marshall Tire Group, Inc. | CA7182 | Mine contractor | — |
| — | Marshall, Miller & Associates, Inc. | CF4T | Mine contractor | — |
| — | Martin and Company | CB3185 | Mine contractor | — |
| — | Martin Engineering Co Inc | CKXC | Mine contractor | — |
| — | MARTIN EQUIPMENT OF IL INC | C3CL | Mine contractor | — |
| — | Martin Marietta | CB7127 | Mine contractor | — |
| — | Martin Marietta - Salisbury Ops Svcs | CB9338 | Mine contractor | — |
| — | Martin Marietta Materials Southwest, LLC | CC335 | Mine contractor | — |
| — | Martin Marietta Materials, Inc | CB8611 | Mine contractor | — |
| — | Martin Marietta Virginia West Maintenance | CZ300 | Mine contractor | — |
| — | Martin mechanical services | CC8400 | Mine contractor | — |
| — | Martin's Power Sweeping | CB4682 | Mine contractor | — |
| — | Martinez Electric, LLC | CB4411 | Mine contractor | — |
| — | Martinez Welding | CC2551 | Mine contractor | — |
| — | Mashuda Contractors, Inc. | CW510 | Mine contractor | — |
| — | Mason City Overhead Door Inc | CB018 | Mine contractor | — |
| — | Mason's Field Service | CB0016 | Mine contractor | — |
| — | MASS Technologies Inc. | CA2044 | Mine contractor | — |
| — | Massie Reclamation Inc | CC0D | Mine contractor | — |
| — | MASTIFF TREE CARE, LLC | CC8127 | Mine contractor | — |
| — | Matheson Drilling Inc | CBJL | Mine contractor | — |
| — | Mathews Excavating | CA8134 | Mine contractor | — |
| — | MATRIX TECHNOLOGIES, INC. | CF709 | Mine contractor | — |
| — | Matt Jacobson Trucking | CB6033 | Mine contractor | — |
| — | Matt Tille Enterprises | CA4192 | Mine contractor | — |
| — | Matthew, David & Thomas, Inc. | CY038 | Mine contractor | — |
| — | Maurer & Scott Inc | CCV6 | Mine contractor | — |
| — | Maurer Electric, Inc. | CA8491 | Mine contractor | — |
| — | Maverick Fabrications LLC | CC2413 | Mine contractor | — |
| — | Maviro Inc. dba RMIS | CS694 | Mine contractor | — |
| — | Mavo Systems Inc | CIAZ | Mine contractor | — |
| — | Max Arnold & Sons Inc | CTHL | Mine contractor | — |
| — | Maxam North America Inc. | CEJ7 | Mine contractor | — |
| — | Maxim Crane Works | CHTN | Mine contractor | — |
| — | Maxim Drilling Co., Inc | CB7712 | Mine contractor | — |
| — | MaxSteel Fabrication LLC | CC0369 | Mine contractor | — |
| — | Maxwell Land Management LLC | CC6035 | Mine contractor | — |
| — | Maxxim Rebuild Company, LLC | CF457 | Mine contractor | — |
| — | Maxxim Shared Services LLC | CA3733 | Mine contractor | — |
| — | May Towing LLC | CB8110 | Mine contractor | — |
| — | Mayne Construction | CA8344 | Mine contractor | — |
| — | Mazzella Lifting Technologies, Inc | CC6279 | Mine contractor | — |
| — | MC Mechanical & Piping LLClc | CC2250 | Mine contractor | — |
| — | MC MILLEN MAINTENANCE | CH398 | Mine contractor | — |
| — | MC Welding Service LLC | CB2838 | Mine contractor | — |
| — | McAdoo's Inc | CB1786 | Mine contractor | — |
| — | Mcafees Welding & Repair | C3CN | Mine contractor | — |
| — | McAljon | CT288 | Mine contractor | — |
| — | McAninch Corporation | C4EV | Mine contractor | — |
| — | MCC, Inc | CB9216 | Mine contractor | — |
| — | McCallum Powder, LLC. | CB5388 | Mine contractor | — |
| — | Mccallum Rock Drilling | CLKI | Mine contractor | — |
| — | McCarter Electric | CF880 | Mine contractor | — |
| — | McCarthy Industrial Contractors Inc | CA7450 | Mine contractor | — |
| — | McCarthy Tire Service Co | CE13 | Mine contractor | — |
| — | Mcclanahan Corp | C6NV | Mine contractor | — |
| — | Mcclelland Welding, LLC | CQ5D | Mine contractor | — |
| — | Mcclung-Logan Equip Co Inc | C1QX | Mine contractor | — |
| — | McConnell Sand and Stone LLC | CA9772 | Mine contractor | — |
| — | McCourt & Sons Equipment, Inc. | CA1283 | Mine contractor | — |
| — | McCoy Construction & Forestry Inc | CB7832 | Mine contractor | — |
| — | McCoy Corporation, Inc. | CB7166 | Mine contractor | — |
| — | McCraren Brothers Compliance | CA5171 | Mine contractor | — |
| — | McCrary Enterprises Inc | CB1953 | Mine contractor | — |
| — | Mccumpsey Construction Co | CFRE | Mine contractor | — |
| — | McDaniel Mobile Welding | CC8754 | Mine contractor | — |
| — | McDaniel Service, LLC | CC1672 | Mine contractor | — |
| — | MCDONALD ELECTRIC INC. | CN367 | Mine contractor | — |
| — | MCDONALD EXTERMINATORS | CZ733 | Mine contractor | — |
| — | McDonough Construction Rentals | C6SA | Mine contractor | — |
| — | McDowell Crane & Rigging | CA8280 | Mine contractor | — |
| — | Mcgeorge Contracting Co Inc | CRR7 | Mine contractor | — |
| — | McGiffen Trucking | CV886 | Mine contractor | — |
| — | McGillivray Environmental | CV299 | Mine contractor | — |
| — | McGlocklin Welding | CC1142 | Mine contractor | — |
| — | McGree Corp | CM734 | Mine contractor | — |
| — | McGriff Tire Company | CLH5 | Mine contractor | — |
| — | Mckinley Tire Sales & Service | CB433 | Mine contractor | — |
| — | McKinney Computer Service Inc | CC3547 | Mine contractor | — |
| — | McKinstry | CC7339 | Mine contractor | — |
| — | McLeod Express LLC | CA2875 | Mine contractor | — |
| — | McMurray Welding | CZ946 | Mine contractor | — |
| — | McMurtry and Sons welding and fabrication llc | CC3785 | Mine contractor | — |
| — | McNally-Nimergood Co. | CA6241 | Mine contractor | — |
| — | MCS | CK351 | Mine contractor | — |
| — | MD Nut and Bolt | CA4225 | Mine contractor | — |
| — | MD Trucking, Inc. | CD554 | Mine contractor | — |
| — | MDC Contracting, LLC | CJ648 | Mine contractor | — |
| — | MDL Contracting Inc. | CL452 | Mine contractor | — |
| — | Mead Enterprises, Inc. | CQ335 | Mine contractor | — |
| — | Mechanical Industries Inc | CRIZ | Mine contractor | — |
| — | Mechanical Service & Systems I | CZWJ | Mine contractor | — |
| — | MechTech Inc. | CC2677 | Mine contractor | — |
| — | Meeks Mobile Welding LLC | CC1549 | Mine contractor | — |
| — | Mehas Construction, Inc. | CC7568 | Mine contractor | — |
| — | Meise Construction Inc | CN583 | Mine contractor | — |
| — | MEISER & EARL, INC. | CB1812 | Mine contractor | — |
| — | Mel Daniel Industrial | CA0495 | Mine contractor | — |
| — | Melanson Logging | CA2201 | Mine contractor | — |
| — | Meldrum Mechanical Services Inc | CZ632 | Mine contractor | — |
| — | Melgaard Construction Co Inc | CICS | Mine contractor | — |
| — | Melink Solar LLC | CC8949 | Mine contractor | — |
| — | MELLER EXCAVATING & ASPHALT | CA8216 | Mine contractor | — |
| — | Mellott Company | CZ62 | Mine contractor | — |
| — | Mendoza Boulders Inc | CVZM | Mine contractor | — |
| — | Mendoza Contracting | CC0112 | Mine contractor | — |
| — | Meridian Engineering Co | CG647 | Mine contractor | — |
| — | Meridian Industrial & Welding Services | CY904 | Mine contractor | — |
| — | Meriwether Site Solutions | CC5539 | Mine contractor | — |
| — | Merrell Bros | CC3817 | Mine contractor | — |
| — | Mersino Dewatering Inc. | CA7128 | Mine contractor | — |
| — | Metal Tech | CA6515 | Mine contractor | — |
| — | Metalcoat, Inc of Fl | CMX9 | Mine contractor | — |
| — | Metallogeny, Inc. | CW972 | Mine contractor | — |
| — | Metalock, Inc. | CQ589 | Mine contractor | — |
| — | Metrek Technologies, LLC | CC6282 | Mine contractor | — |
| — | Metro East Industries Inc | CIUX | Mine contractor | — |
| — | Metro Elevator | CC8202 | Mine contractor | — |
| — | Metro-Tek Electrical Services, Inc. | CR008 | Mine contractor | — |
| — | Metropolitan Environmental Services | CA5687 | Mine contractor | — |
| — | MetroPower, Inc | C2KK | Mine contractor | — |
| — | Metso Outotec USA Inc. | CDZJ | Mine contractor | — |
| — | Meyer Welding, LLC | CB7181 | Mine contractor | — |
| — | MG Machinery | CC6194 | Mine contractor | — |
| — | MGX Equipment Services, LLC | CC4747 | Mine contractor | — |
| — | MH Equipment | CG678 | Mine contractor | — |
| — | MIC Steel, Inc | CR315 | Mine contractor | — |
| — | MiCa Enterprises,Inc. | CZ654 | Mine contractor | — |
| — | Micah welding | CC5828 | Mine contractor | — |
| — | Michael Bailey Electrical Consultants, Inc. | CZ202 | Mine contractor | — |
| — | Michael J Molnar Equipment Repair LLC | CC4638 | Mine contractor | — |
| — | Michael Smith/Contractor | CB0943 | Mine contractor | — |
| — | Michels Road & Stone, Inc. | CC5594 | Mine contractor | — |
| — | Michigan CAT, ATTN: Human Resources | CZ0M | Mine contractor | — |
| — | MIchigan Marine Services | CB1074 | Mine contractor | — |
| — | Micronics Engineered Filtration Group Inc. | CC5975 | Mine contractor | — |
| — | Mid Country Machinery LLC | CA7717 | Mine contractor | — |
| — | Mid Ga Electrical Servicesinc | CVBJ | Mine contractor | — |
| — | Mid GA Hydroseeding LLC | CC5723 | Mine contractor | — |
| — | Mid States Energy Co. LLC | CB5410 | Mine contractor | — |
| — | Mid Tech Power & Control | CVDJ | Mine contractor | — |
| — | Mid Valley Electric, Inc. | CX942 | Mine contractor | — |
| — | Mid Western Industrial Rubber Inc. | CC3246 | Mine contractor | — |
| — | Mid-Ark Environmental | CB7108 | Mine contractor | — |
| — | Mid-State Contracting Llc | CBQM | Mine contractor | — |
| — | Mid-State Electric of Highland County LLC | CA1633 | Mine contractor | — |
| — | Mid-West Drilling & Blasting | CF725 | Mine contractor | — |
| — | Mid-West Railroad Construction, LLC | CF819 | Mine contractor | — |
| — | Midark Environmental Services, Inc. | CA6991 | Mine contractor | — |
| — | Middle Georgia Safety Inc | C5PK | Mine contractor | — |
| — | Middleton Backhoe Service | CS557 | Mine contractor | — |
| — | Mideast Machinery Movers, Inc. | CL610 | Mine contractor | — |
| — | MidSouth Fab LLC | CC3446 | Mine contractor | — |
| — | Midsouth Machine Shop | CA4034 | Mine contractor | — |
| — | Midstate Electric | CB3222 | Mine contractor | — |
| — | Midstate Steel Inc | CLGG | Mine contractor | — |
| — | Midwest Automation & Custom Fabrication, Inc. | CA6906 | Mine contractor | — |
| — | Midwest Automation, LLC | CA2014 | Mine contractor | — |
| — | Midwest Doors Inc | CC378 | Mine contractor | — |
| — | Midwest Industrial Supply Inc | CZKG | Mine contractor | — |
| — | Midwest Mechanical & Welding, LLC | CC4273 | Mine contractor | — |
| — | Midwest Mechanical Industrial Services | CA8144 | Mine contractor | — |
| — | Midwest Mine Services- Hall Industrial Company | CF522 | Mine contractor | — |
| — | Midwest Mining Solutions llc | CC6847 | Mine contractor | — |
| — | Midwest Mobile Tech Inc. | CC2817 | Mine contractor | — |
| — | Midwest Paving LLC | CC4278 | Mine contractor | — |
| — | Midwest Pottyhouse | CV599 | Mine contractor | — |
| — | Midwestern Metals Inc | CM327 | Mine contractor | — |
| — | Mielke Electric Works | CA5377 | Mine contractor | — |
| — | Migliorini Builders | CC4558 | Mine contractor | — |
| — | Mike Blasi Trucking, Inc. | CS277 | Mine contractor | — |
| — | Mike Browning DBA Safety Training Consultant | CC1445 | Mine contractor | — |
| — | Mike Morgan Industrial, LLC | CB0425 | Mine contractor | — |
| — | Mike's Masonry | CC5738 | Mine contractor | — |
| — | Mike's Sealing & Stripping LLC | CA2427 | Mine contractor | — |
| — | Mikes Specialty Welding | CTFT | Mine contractor | — |
| — | Milan Landscape | CC8799 | Mine contractor | — |
| — | Miles Exploration LLC | CC5053 | Mine contractor | — |
| — | Miles Supply Quarrying Solutions Inc. | CA6311 | Mine contractor | — |
| — | Milestone Contractors LP | CB149 | Mine contractor | — |
| — | Milestone Materials U.S. LLC | CJ018 | Mine contractor | — |
| — | Millennium Machinery Parts & Service Corp | CC1253 | Mine contractor | — |
| — | Miller Bros Construction | C8LR | Mine contractor | — |
| — | Miller Bros Giant Tire Service-Orlando, Inc. | CM576 | Mine contractor | — |
| — | Miller Contracting Services, LLC | CS956 | Mine contractor | — |
| — | Miller Electric Company | CJGN | Mine contractor | — |
| — | Miller Electric Company | CP620 | Mine contractor | — |
| — | Miller Equipment Company, Inc. | CT061 | Mine contractor | — |
| — | Miller Fabrication & Constr | C6KJ | Mine contractor | — |
| — | Miller Mechanic Services LLC | CC9353 | Mine contractor | — |
| — | Miller Quarry LLC | CA2006 | Mine contractor | — |
| — | Miller Welding Service Inc | CT7Y | Mine contractor | — |
| — | Miller-Eads Co., Inc. | CC1367 | Mine contractor | — |
| — | Millerick Engineering | CQ287 | Mine contractor | — |
| — | Milling Machinery Inc | CPWH | Mine contractor | — |
| — | Mills Industrial Const Inc | CRWT | Mine contractor | — |
| — | Mills Service Inc | CA9414 | Mine contractor | — |
| — | Mills Welding Fabrication & Rep | CB173 | Mine contractor | — |
| — | Miltech Analytical Services, Inc. | CA1348 | Mine contractor | — |
| — | Mimms Contractors Incorporated | CB6863 | Mine contractor | — |
| — | Mine Drilling Services, LLC | CA0573 | Mine contractor | — |
| — | mine machinery | CA1480 | Mine contractor | — |
| — | Mine Pro Corp | CC7329 | Mine contractor | — |
| — | Mine Professionals of Arizona, Inc. | CC5517 | Mine contractor | — |
| — | Mine Rite Technologies, LLC | CL683 | Mine contractor | — |
| — | Mine Service Co Inc | CA5G | Mine contractor | — |
| — | Mine Service Inc. | CK4G | Mine contractor | — |
| — | Mine Services Company, Inc. | CA1777 | Mine contractor | — |
| — | Mine Site Technologies (USA) Inc | CY119 | Mine contractor | — |
| — | MineARC Systems | CS877 | Mine contractor | — |
| — | Miner Southwest, LLC | CA3983 | Mine contractor | — |
| — | Mineral Technologies Inc | CC4613 | Mine contractor | — |
| — | Minerals Refining-FG LLC | CC3554 | Mine contractor | — |
| — | Minesense Technologies US Ltd | CC6649 | Mine contractor | — |
| — | MineTech Equipment Repair | CC0977 | Mine contractor | — |
| — | Mining & Development Management Inc | CB8928 | Mine contractor | — |
| — | Mining & Env. Services | CA116 | Mine contractor | — |