| Abenakiite-(Ce) | Na₂₆Ce₆(Si₆O₁₈)(PO₄)₆(CO₃)₆(SO₂)O | Trigonal | — | — |
| Abramovite | Pb₂SnInBiS₇ | Triclinic | — | — |
| Acanthite | Ag₂S | Monoclinic | — | — |
| Acmonidesite | (NH₄,K,Pb)₈NaFe²⁺₄(SO₄)₅Cl₈ | Orthorhombic | — | — |
| Adolfpateraite | K(UO₂)(SO₄)(OH)(H₂O) | Monoclinic | — | — |
| Adranosite | (NH₄)₄NaAl₂(SO₄)₄Cl(OH)₂ | Tetragonal | — | — |
| Adranosite-(Fe) | (NH₄)₄NaFe₂(SO₄)₄Cl(OH)₂ | Tetragonal | — | — |
| Afghanite | (Na,K)₂₂Ca₁₀(Si₂₄Al₂₄)O₉₆(SO₄)₆Cl₆ | Trigonal | — | — |
| Agmantinite | Ag₂MnSnS₄ | Orthorhombic | — | — |
| Aguilarite | Ag₄SeS | Orthorhombic | 2.5 | — |
| Aikinite | CuPbBiS₃ | Orthorhombic | — | — |
| Aiolosite | Na₂(Na₂Bi)(SO₄)₃Cl | Hexagonal | — | — |
| Aktashite | Cu₆Hg₃As₄S₁₂ | Trigonal | — | — |
| Alabandite | MnS | Cubic | — | 4.19 g/cm³ |
| Alacránite | As₈S₉ | Monoclinic | 1.5 | — |
| Albertiniite | Fe²⁺(SO₃)·3H₂O | Monoclinic | — | — |
| Alburnite | Ag₈GeTe₂S₄ | Cubic | — | — |
| Alcaparrosaite | K₃Ti⁴⁺Fe³⁺(SO₄)₄O(H₂O)₂ | Monoclinic | — | — |
| Aldridgeite | (Cd,Ca)(Cu,Zn)₄(SO₄)₂(OH)₆·3H₂O | Monoclinic | — | — |
| Aleksite | PbBi₂Te₂S₂ | Trigonal | 2.0 | — |
| Alexearlite | Hg₃(MoO₄)S₂ | Orthorhombic | — | — |
| Alloclasite | CoAsS | Monoclinic | — | 6.26 g/cm³ |
| Alloriite | (Na,K,Ca)₂₄(Na,Ca)₄Ca₄(Si,Al)₄₈O₉₆(SO₄)₄(SO₃,CO₃)₂(OH,Cl)₂(H₂O,OH)₄ | Trigonal | — | — |
| Alpersite | Mg(SO₄)·7H₂O | Monoclinic | 2.5 | — |
| Alterite | Zn₂Fe³⁺₄(SO₄)₄(C₂O₄)₂(OH)₄ * 17H₂O | Monoclinic | — | — |
| Alum-(K) | KAl(SO₄)₂·12H₂O | Cubic | — | — |
| Alum-(Na) | NaAl(SO₄)₂·12H₂O | Cubic | — | — |
| Aluminite | Al₂SO₄(OH)₄·7H₂O | Monoclinic | — | — |
| Aluminocopiapite | (Al,Mg)Fe³⁺₄(SO₄)₆(OH,O)₂·20H₂O | Triclinic | — | — |
| Aluminocoquimbite | AlFe(SO₄)₃·9H₂O | Trigonal | — | — |
| Aluminopyracmonite | (NH₄)₃Al(SO₄)₃ | Trigonal | — | — |
| Alumoklyuchevskite | K₃Cu²⁺₃AlO₂(SO₄)₄ | Triclinic | 2.5 | — |
| Alunite | KAl₃(SO₄)₂(OH)₆ | Trigonal | — | — |
| Alunogen | Al₂(SO₄)₃(H₂O)₁₂·5H₂O | Triclinic | — | — |
| Alwilkinsite-(Y) | Y(UO₂)₃(SO₄)₂O(OH)₃(H₂O)₇·7H₂O | Orthorhombic | — | — |
| Amarantite | Fe³⁺₂O(SO₄)₂·7H₂O | Triclinic | 2.5 | — |
| Amarillite | NaFe³⁺(SO₄)₂·6H₂O | Monoclinic | — | — |
| Ambrinoite | [K,(NH₄)]₂(As,Sb)₆(Sb,As)₂S₁₃·H₂O | Triclinic | — | — |
| Ammonioalunite | (NH)₄Al₃(SO₄)₂(OH)₆ | Trigonal | — | — |
| Ammoniojarosite | (NH)₄Fe³⁺₃(SO₄)₂(OH)₆ | Trigonal | — | — |
| Ammoniomagnesiovoltaite | (NH₄)₂Mg₅Fe³⁺₃Al(SO₄)₁₂·18H₂O | Cubic | — | — |
| Ammoniomathesiusite | (NH₄)₅(UO₂)₄(SO₄)₄(VO₅)₄·H₂O | Tetragonal | — | — |
| Ammoniovoltaite | (NH₄)₂Fe²⁺₅Fe³⁺₃Al(SO₄)₁₂(H₂O)₁₈ | Cubic | — | — |
| Ammoniozippeite | (NH₄)₂[(UO₂)₂(SO₄)O₂]*H₂O | Orthorhombic | — | — |
| Amoraite | Ca₁₂Al₆(OH)₃₆(CO₃)₂(SO₃)·15H₂O | Triclinic | — | — |
| Anandite | BaFe²⁺₃(Si₃Fe³⁺)O₁₀S(OH) | Monoclinic | — | — |
| Andreadiniite | CuHgAg₇Pb₇Sb₂₄S₄₈ | Monoclinic | — | — |
| Andrieslombaardite | RhSbS | Cubic | — | 7.62 g/cm³ |
| Anglesite | PbSO₄ | Orthorhombic | — | 6.34 g/cm³ |
| Anhydrite | CaSO₄ | Orthorhombic | 3.5 | 2.98 g/cm³ |
| Anilite | Cu₇S₄ | Orthorhombic | 3.0 | — |
| Annivite-(Zn) | Cu₆(Cu₄Zn₂)Bi₄S₁₂S | Cubic | — | — |
| Anorpiment | As₂S₃ | Triclinic | — | — |
| Anorthominasragrite | (V₄+O)(SO₄) * 5H₂O | Triclinic | — | — |
| Antlerite | Cu²⁺₃SO₄(OH)₄ | — | — | — |
| Antofagastaite | Na₂Ca(SO₄)₂·1.5H₂O | — | — | — |
| Aphthitalite | K₃Na(SO₄)₂ | Trigonal | 3.0 | 2.75 g/cm³ |
| Apjohnite | Mn²⁺Al₂(SO₄)₄ * 2₂H₂O | Monoclinic | — | — |
| Aplowite | Co(SO₄)·4H₂O | Monoclinic | — | — |
| Apuanite | Fe²⁺Fe³⁺₄Sb³⁺₄O₁₂S | Tetragonal | — | — |