| Abellaite | NaPb₂(CO₃)₂(OH) | Trigonal | — | — |
| Abelloemringerite | Cu₂Pb₂Mn³⁺Mn⁴⁺₃O₁₁(OH)(H₂O)₂·H₂O | Orthorhombic | — | — |
| Abenakiite-(Ce) | Na₂₆Ce₆(Si₆O₁₈)(PO₄)₆(CO₃)₆(SO₂)O | Trigonal | — | — |
| Abernathyite | K(UO₂)(AsO₄)·3H₂O | Tetragonal | — | — |
| Abhurite | Sn²⁺₂₁O₆(OH)₁₄Cl₁₆ | Trigonal | 2.0 | — |
| Abswurmbachite | Cu²⁺(Mn³⁺)₆O₈(SiO₄) | Tetragonal | 6.5 | 4.96 g/cm³ |
| Abuite | CaAl₂(PO₄)₂F₂ | Orthorhombic | — | — |
| Achalaite | Fe²⁺TiNb₂O₈ | Monoclinic | — | — |
| Achyrophanite | (K,Na)₃(Fe³⁺,Ti,Al,Mg)₅O₂(AsO₄)₅ | Orthorhombic | — | — |
| Acmonidesite | (NH₄,K,Pb)₈NaFe²⁺₄(SO₄)₅Cl₈ | Orthorhombic | — | — |
| Actinolite | Ca₂(Mg,Fe)₅[OH|Si₄O₁₁]₂ | Monoclinic | — | — |
| Acuminite | SrAlF₄(OH)·H₂O | Monoclinic | 3.5 | — |
| Adachiite | CaFe²⁺₃Al₆(Si₅AlO₁₈)(BO₃)₃(OH)₃(OH) | Trigonal | 7.0 | — |
| Adamite | Zn₂AsO₄(OH) | Orthorhombic | 3.5 | 4.23 g/cm³ |
| Adamsite-(Y) | NaY(CO₃)₂·6H₂O | Triclinic | 3.0 | — |
| Addibischoffite | Ca₂Al₆Al₆O₂₀ | Triclinic | — | — |
| Adelite | CaMgAsO₄(OH) | Orthorhombic | 5.0 | — |
| Admontite | MgB₆O₁₀·7H₂O | Monoclinic | — | — |
| Adolfpateraite | K(UO₂)(SO₄)(OH)(H₂O) | Monoclinic | — | — |
| Adranosite | (NH₄)₄NaAl₂(SO₄)₄Cl(OH)₂ | Tetragonal | — | — |
| Adranosite-(Fe) | (NH₄)₄NaFe₂(SO₄)₄Cl(OH)₂ | Tetragonal | — | — |
| Adrianite | Ca₁₂(Al₄Mg₃Si₇)O₃₂Cl₆ | Cubic | — | — |
| Aegirine | NaFe³⁺Si₂O₆ | Monoclinic | 6.3 | — |
| Aegirine-augite | (Ca,Na)(Fe³⁺,Mg,Fe²⁺)Si₂O₆ | Monoclinic | — | — |
| Aenigmatite | Na₄[Fe²⁺₁₀Ti₂]O₄[Si₁₂O₃₆] | Triclinic | 5.5 | — |
| Aerinite | (Ca,Na)₆(Fe³⁺,Fe²⁺,Mg,Al)₄(Al,Mg)₆Si₁₂O₃₆(OH)₁₂(CO₃)·12H₂O | — | 3.0 | 2.48 g/cm³ |
| Aerugite | Ni₈.₅(AsO₄)₂As⁵⁺O₈ | Trigonal | 4.0 | 5.85 g/cm³ |
| Aeschynite-(Ce) | Ce(TiNb)O₆ | Orthorhombic | — | — |
| Aeschynite-(Nd) | Nd(TiNb)O₆ | — | — | — |
| Aeschynite-(Y) | Y(TiNb)O₆ | Orthorhombic | — | — |
| Afghanite | (Na,K)₂₂Ca₁₀(Si₂₄Al₂₄)O₉₆(SO₄)₆Cl₆ | Trigonal | — | — |
| Afmite | Al₃(OH)₄(H₂O)₃(PO₄)(PO₃OH)·H₂O | Triclinic | — | — |
| Afwillite | Ca₃[SiO₃(OH)]₂·2H₂O | Monoclinic | — | — |
| Agaite | Pb₃Cu²⁺Te⁶⁺O₅(OH)₂(CO₃) | Orthorhombic | — | — |
| Agakhanovite-(Y) | YCa☐₂KBe₃Si₁₂O₃₀ | Hexagonal | 6.0 | — |
| Agardite-(Ce) | CeCu²⁺₆(AsO₄)₃(OH)₆·3H₂O | Hexagonal | 3.0 | — |
| Agardite-(La) | LaCu²⁺₆(AsO₄)₃(OH)₆·3H₂O | Hexagonal | — | — |
| Agardite-(Nd) | NdCu²⁺₆(AsO₄)₃(OH)₆·3H₂O | Hexagonal | — | — |
| Agardite-(Y) | YCu²⁺₆(AsO₄)₃(OH)₆·3H₂O | Hexagonal | — | — |
| Agrellite | NaCa₂Si₄O₁₀F | Triclinic | 5.5 | — |
| Agricolaite | K₄(UO₂)(CO₃)₃ | Monoclinic | 4.0 | 3.53 g/cm³ |
| Agrinierite | K₂Ca[(UO₂)₃O₃(OH)₂]₂·5H₂O | Orthorhombic | — | — |
| Agujaite | Na₆Al₆(H₂O)₁₅(OH)₃(AsO₄)₅(AsO₃OH)₃⋅3H₂O | Trigonal | — | — |
| Aheylite | Fe²⁺Al₆(PO₄)₄(OH)₈·4H₂O | Triclinic | — | — |
| Ahlfeldite | NiSeO₃·2H₂O | Monoclinic | — | — |
| Ahrensite | γ-Fe₂(SiO₄) | Cubic | 6.0 | — |
| Aiolosite | Na₂(Na₂Bi)(SO₄)₃Cl | Hexagonal | — | — |
| Ajoite | K₃Cu²⁺₂₀Al₃Si₂₉O₇₆(OH)₁₆·8H₂O | Triclinic | — | — |
| Akaganeite | (Fe³⁺,Ni²⁺)₈(OH,O)₁₆Cl₁.₂₅·nH₂O | Monoclinic | — | — |
| Akaogiite | TiO₂ | Monoclinic | — | 3.86 g/cm³ |
| Akasakaite-(Ce) | (CaCe)(AlAlMn²⁺)O[Si₂O₇][SiO₄](OH) | Monoclinic | — | — |
| Akasakaite-(La) | (CaLa)(AlAlMn²⁺)O[Si₂O₇][SiO₄](OH) | Monoclinic | — | — |
| Akatoreite | Mn²⁺₉Al₂Si₈O₂₄(OH)₈ | Triclinic | 6.0 | — |
| Akdalaite | Al₅O₇(OH) | Hexagonal | — | — |
| Akhtenskite | MnO₂ | Hexagonal | 2.0 | — |
| Akimotoite | MgSiO₃ | Trigonal | — | — |
| Aklimaite | Ca₄[Si₂O₅(OH)₂](OH)₄·5H₂O | Monoclinic | — | — |
| Akopovaite | Al₄Li₂(OH)₁₂(CO₃)(H₂O)₃ | Monoclinic | — | — |
| Akrochordite | Mn²⁺₅(AsO₄)₂(OH)₄·4H₂O | Monoclinic | 3.5 | — |
| Aksaite | MgB₆O₇(OH)₆·2H₂O | Orthorhombic | — | — |