ore-leaching tank - pad construction
- orthograde
- orthogranite
- orthographic
- orthogyre
- orthohexact(ine)
- orthohydrous
- orthohydrous coal
- orthohydrous maceral
- ortholignitous coal
- ortholimestone
- ortholith
- orthomagmatic
- orthomicrite
- orthomicrosparite
- orthomorphic
- orthomorphism
- orthopentact(ine)
- orthophoto
- orthophotomap
- orthophotomosaic
- orthophyre
- orthophyric
- orthophyric texture
- orthopinacoid
- orthopinakiolite
- orthopterian
- orthopyroxen
- orthopyroxene
- orthoquartzite
- orthorhombic
- orthorhombic lattice
- orthorhombic layer
- orthorhombic pyroxene
- orthorhombic symmetry
- orthorhombic system
- orthorock
- orthoschist
- orthoscope
- orthose
- orthoselection