The list of 'M' refiners/mints/hallmarks:

• Mastiff Metals
• Materion (to do)
• M & B Mining (Omega)
• MCR/Mehlos Refinery (to do)
• MEE (to do)
• Messers Manilal Chimanlal & Co.
• Metalrex (to do)
• Midas Metals (to do)
• Midsouth Smelters
• MMI (to do)
• MMM (to do)
• M/W. E. Mowrey (to do)
• Montana Assay
• Montana Gold and Silver Corporation
• Monumental Mine
• MSC (to do)