Chwilio am Fwynau (Saesneg yn unig)
- Mackinawite
- Magnesiohornblende
- Magnesite
- Magnetite
- Malachite
- Manganhumite
- Manganite
- Manganosite
- Marcasite
- Margarite
- Massicot
- Matildite
- Mattheddleite
- Melanterite
- Metahalloysite
- Microcline
- Millerite
- Mimetite
- Minium
- Molybdenite
- Monazite-(Ce)
- Monazite-(Nd)
- Monohydrocalcite
- Morenosite
- Mottramite
- Muscovite