auro - bart
- aurora
- auroral zone
- australite
- authigene
- authigenesis
- authigenic
- authigenic element
- authigenic mineral
- authigenous
- auto injection
- autobreccia
- autobreccited lava
- autocatalysis
- autochthone
- autochthonous
- autochthonous coal
- autochthonous deposit
- autochthonous fold
- autochthonous granite
- autochthonous limestone
