Material Index
| Name | Formula | Classifications | Members | Image | Lines | Spectra | Techniques | Tags |
|---|---|---|---|---|---|---|---|---|
| Aragonite (group) | XCO3, X=Ca,Pb,Sr,Ba | — | Witherite, Strontianite, Aragonite, Cerussite | 0 | 0 | — | Carbonate , Group | |
| Arctite | Ba(Ca7Na5)(PO4)4(PO4)2F3 | — | — | 8 | 0 | — | Mineral, Orthophosphate , Phosphate | |
| Arfvedsonite | NaNa2(FeII4FeIII)Si8O22(OH)2 | Arfvedsonite root name group | — | 0 | 0 | — | Mineral, Hydroxide , Silicate | |
| Arfvedsonite root name group | ANa2(ZII4FeIII)Si8O22(OH,F,Cl)2 | Sodium amphibole | Magnesio-arfvedsonite, Arfvedsonite, Potassic-arfvedsonite, Magnesio-fluoro-arfvedsonite, Potassic-magnesio-arfvedsonite, Potassic-magnesio-fluoro-arfvedsonite | 0 | 0 | — | Group , Silicate | |
| Argentite | Ag2S | Silver sulphide | — | 0 | 0 | — | Sulphide | |
| Argon | Ar | — | — | 6 | 0 | — | Element | |
| Argutite | GeO2 | Rutile (group) | — | 0 | 0 | — | Mineral, Simple oxide | |
| Armenite | BaCa2(Al6Si9)O30·2H2O | Osumilite (group) | — | 0 | 0 | — | Hydrated , Mineral, Aluminosilicate | |
| Arsenic | As | — | Arsenolamprite | 13 | 0 | — | Mineral, Element | |
| Arsenolamprite | As | Arsenic | — | 0 | 0 | — | Mineral | |
| Arsenuranylite | Ca(UO2)4(AsO4)2(OH)4·6H2O | — | — | 3 | 0 | — | Arsenate , Hydrated , Uranyl , Mineral, Hydroxide | |
| Astatine | At | — | — | 3 | 0 | — | Element | |
| Augite | (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 | Clinopyroxene | — | 4 | 2 | EDS | Mineral, Silicate | |
| Auriacusite | FeIIICuII(AsO4)O | Olivenite (group) | — | 0 | 0 | — | Arsenate , Mineral | |
| Aurostibite | AuSb2 | Pyrite (group) | — | 0 | 0 | — | Mineral |
