| Mineral/rock | Derived from or for |
| Actinolite | Greek actino = ray and lithos = stone in reference to its occurrence in bundles of radiating needles |
| Agalmatolite | Greek algalma = image and lithos = stone as it was carved by the Chinese |
| Agate | locality at the River Achates, now Drillo in Sicily, where it was originally found
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| Aggregate | Latin aggregatus = to lead to a flock, add to |
| Akageneite | locality at Akagame mine, Iwate Prefecture, Japan |
| Alabandite | locality at Alabanda in Caria, Asia Minor |
| Alabaster | ancient ointment jars called alabastra and perhaps Alabastron in Egypt; alternatively from Egyptian a-la-baste = ship of the Goddess Ebaste = Bubaste |
| Albite | Latin albus = white, for its color |
| Alexandrite | Czar Alexander II (1818-1881) of Russia |
| Allanite | Thomas Allan (1777-1833), Scottish mineralogist and first observer |
| Almandine (garnet) | Alabanda, Asia Minor, where garnets were cut and polished |
| Aluminum | Latin alumen = alum, original name for natural aluminum sulfate |
| Alunite | Latin alumen = alum (see above) and French alun = alum |
| Amazonite | locality at Amazon River, South America |
| Amber | French ambre from Arabic anbar = ambergris (now obsolete) |
| Amblygonite | Greek amblys = dull, obtuse and gonia = angle, in reference to cleavage angle |
| Amethyst | Latin amethystus and Greek amethystos = not drunken as the stone and plant was thought to orevent intoxication |
| Amosite | acronym of Asbestos Mines of South Africa |
| Analcime | Greek analkis = without strength due to its weak electrical properties when heated or rubbed |
| Anatase | Greek anatasis = extension because of the greater length of the common pyramid as compared with other tetragonal minerals |
| Andradite (garnet) | J.B.d'Andrada e Silva (1763-1838), Brazilian mineralogist and first observer |
| Anhydrite | Greek anhydros = dry or without water |
| Anorthite | Greek for not straight, because of its triclinic symmetry |
| Antimony | Latin from Greek anti = against plus monos = a metal seldom found alone |
| Andalusite | locality at Andalusia, Spain |
| Anthophyllite | neo-Latin anthophyllum = clove for its brown color, Greek lithos = stone |
| Apatite | Greek apate = deceit since it was often mistaken for other minerals |
| Aphthitalite | Greek aphthitos = unchangeable or indestructible, alis = salt, and lithos = stone since it is very stable in air |
| Aquamarine | Latin aqua marina = seawater alluding to its pale bluish-green color |
| Aragonite | locality at Aragon, Spain, where it was first identified |
| Arcanite | Medieval Latin alchemical name, Arcanum duplicatum = double secret |
| Asbestos | Latin and Greek asbestos = inextinguishable alluding to its early uses as a wick |
| Ascherite | a.k.a Szaibelyle |
| Atacamite | locality at Atacama Desert, Chile |
| Attapulgite | locality at Attapulgus, Georgia, USA |
| Axinite | Greek axine = ax in reference to its wedge-shaped crystals |
| Azoproit | Russian title for the International Association for the Study of Deep Zones of the Earth's Crust (AZOPRO) since it was found during the preparation of a guidebook for the Association's meeting in Baikal in 1969 |
