Dacite consists mostly of plagioclase feldspar with biotite, hornblende, and pyroxene (augite and/or enstatite). Their commonest minerals are olivine, anorthite, hornblende, augite, biotite and leucite. It is commonly associated with quartz, potassium feldspar, biotite, hornblende and magnetite. Subhedral hornblende and elongated biotite grains are present. For example, schists primarily composed of biotite and muscovite are called mica schists. Gold occurs in quartz veins traversing in BIF, metavolcanics, and hornblende and biotite gneiss. The central plutons are highly evolved two mica (contain both biotite and muscovite) granites. This is separated from a biotite muscovite granite by pegmatites. Rhyolite tuffs contain pumiceous, glassy fragments and small scoriae with quartz, alkali feldspar, biotite, etc. They are granite with granophyric quartz, perthitic potassium feldspar, biotite and magnetite. It may contain minor amounts of hornblende, biotite and other minerals. Nepheline is very abundant and there is also cancrinite, sodalite, scapolite, calcite, biotite and hornblende. The contained mafic minerals are biotite and amphibole. A granite containing both muscovite and biotite micas is called a binary or "two-mica" granite. Rock types include trachyandesite, trachyte, syenite and amphibole - biotite granite.