Fewer than a dozen minerals account for the vast volume of the world's rocks. These rock-forming minerals make up substantial portions, even the totality, of the rocks they occur in. Here they are, with their formulas.
| Mineral | Approximate Chemical Composition |
| Plagioclase feldspar | NaAlSi3O8 to CaAl2Si2O8 (continuous series) |
| Potassium feldspar | KAlSi3O8 |
| Quartz | SiO2 |
| Pyroxene | (Mg,Fe)2Si2O6 (enstatite series) and (Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6 (augite) |
| Biotite | K(Fe,Mg)3AlSi3O10(OH)2 |
| Muscovite | KAl2(Si3Al)O10(OH,F)2 |
| Hornblende | (Ca,Na)2–3(Mg,Fe,Al)5[(Si,Al)8O22](OH)2 |
| Olivine | (Fe,Mg)2SiO4 |
| Calcite | CaCO3 |
| Dolomite | CaMg(CO3)2 |
