Mineral Assemblage In Igneous Rocks Once the texture of an igneous rock is determined, its name will depend on its mineral assemblage. All common igneous rocks consist largely of ■ Quartz Feldspar (both potassium feldspar and plagioclase). Mica(both muscovite and biotite). ■ Amphibole ■ Pyroxene a OlvineMineral Assemblage In Igneous Rocks ◼ Once the texture of an igneous rock is determined, its name will depend on its mineral assemblage. ◼ All common igneous rocks consist largely of: ◼ Quartz. ◼ Feldspar (both potassium feldspar and plagioclase). ◼ Mica (both muscovite and biotite). ◼ Amphibole. ◼ Pyroxene. ◼ Olivine