HALIDES
| Halite | NaCl | Isometric |
| Fluorite | CaF2 | Isometric |
| Sylvite | KCl | Isometric |
Halides are characterized by the presence of a halogen atom; both the large cations and ions behave as spherical bodies, and the packing leads to structures of highest symmetry. Bonding in the halides is strongly ionic.
SULFATES
| Gypsum | CaSO4-2H2O | Monoclinic |
| Anhydrite | CaSO4 | Orthorhombic |
| Celestite | SrSO4 | Barite |
| Barite | BaSO4 | Orthorhombic |
(SO4)2- complexes are the basis of the minerals.
PHOSPHATES
| Apatite | Ca5PO43(F,Cl,OH) | Hexagonal |
| Monazite | (Ce,La,Y,Th)PO4 | Monoclinic |
(PO4)3- complexes are the basis of the minerals
CARBONATES
| Aragonite | CaCO3 | Orthorhombic |
| Calcite | CaCO3 | Hexagonal |
| Dolomite | CaMg(CO3)2 | Hexagonal |
| Ankerite | CaFe(CO3)2 | Hexagonal |
| Magnesite | MgCO3 | Hexagonal |
| Siderite | FeCO3 | Hexagonal |
| Rhodochrosite | MnCO3 | Hexagonal |
Carbonates have a (CO3)2- complex in the structure; radius ratio relations predict one carbon surrounded by three oxygen in a ring with a residual charge of -2/3 on each oxygen, and a bond of 1 1/3 between each oxygen and the carbon. In the presence of hydrogen, the (CO3)2- group breaks down to form H2O + CO2.
The radius ratio of Ca:O is sufficiently close for there to be two CN for Ca: 6-fold coordination occurs for calcite and 9-fold for aragonite. Calcite is hexagonal, and aragonite is orthorhombic. The oxygen coordinated to Ca are in the CO3 rings, which for calcite and aragonite are in layer perpendicular to c; in Calcite the rings all point the same way, and in aragonite they point in opposite directions from layer to layer.