- O
-
- Occurrence
- Ochre
- Octacube
- Octahedral
- Octahedral cleavage
- Octahedral cube
- Octahedron
- Oil of vitriol
- Oily (luster)
- Oolite
- Oolitic
- Opalesce
- Opalescence
- Opalescent
- Opalization
- Opalize
- Opaque
- Optical
- Optical properties
- Optics
- Ore
- Organic
- Orthorhombic (crystal
system)
- Orthosilicates
- Outcrop
- Oxidation
- Oxidation minerals
- Oxidation zone
- Oxides (group)
- Oxidize
- Oxidized
- Oxidized zone