CoachOlivine is the nesosilicate solid solution . Garnet is a group of cubic nesosilicates , X a divalent ion (Mg, Fe, Mn, Ca), Y a trivalent one (Al, Fe, Cr). A pyroxene is a single-chain inosilicate ; an amphibole is a double-chain inosilicate with hydroxyl, of about . A mica is a sheet silicate with a potassium ion between the sheets, such as muscovite and biotite . A feldspar is an aluminium framework silicate of sodium, potassium or calcium. The plagioclase feldspars form the solid solution albite – anorthite ; the alkali feldspars lie between albite and orthoclase .
| group | end-members or example | class | density () | hardness | cleavage |
|---|---|---|---|---|---|
| olivine | forsterite – fayalite | neso | 3.28–4.39 | 6.5–7 | imperfect; conchoidal fracture |
| garnet | almandine ; pyrope | neso | 4.32; 3.74 | 7–7.5 | none |
| pyroxene | diopside ; enstatite | ino, single chain | 3.22–3.38; 3.2 | 5.5–6.5 | two, at about and |
| amphibole | hornblende | ino, double chain | 3.10–3.28 | 5–6 | two, at and |
| mica | muscovite ; biotite | phyllo | 2.77–2.88; 2.7–3.3 | 2.5–3 | one, perfect: thin flakes |
| feldspar | albite ; anorthite ; orthoclase | tecto | 2.55–2.76 | 6–6.5 | two good, {001} and {010} |
| quartz | tecto | 2.65 | 7 | none; conchoidal fracture | |
| carbonates | calcite ; dolomite | — | 2.71; 2.84 | 3; 3.5–4 | three, rhombohedral |
| iron oxide | magnetite | — | 5.18 | 5.5–6.5 | none; strongly magnetic |