- McNamee Mine, Bath, Aiken County, South Carolina, United States1
- Medina, Orleans County, New York, United States1
- Meigs County, Portland, Ohio, United States1
- Mexico, Audrain County, Missouri, United States1
- Michigan, United States1
- Midland, Cabarrus County, North Carolina, United States1
- Milos, Nisos, Cyclade Islands, Aegean Islands, Greece1
- Mississippi River1
- Mobile, Mobile County, Alabama, United States1
- Mohawk River, New York, United States1
- Mohawk, Ulster County, New York, United States1
- Moluccas, Indonesia 1
- Montclair, Essex County, New Jersey, United States1
- Monte Rose, Liguria, Italy1
- Montgomery, Montgomery County, Alabama, United States1
- Monticello, Jefferson County, Florida, United States1
- Mount Holyoke, Hampshire County, Massachusetts, United States1
- Mount Vesuvius, Napoli province, Campania, Italy1
- Mt. Etna, Sicily, Italy1
- Mumbai, India1