Felsic rocks

Granite (, ) is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, mica and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers.

thumb|upright=1.4|A sample of granodiorite from the Massif Central, France thumb|upright=1.4|QAPF diagram for classification of plutonic rocks. The composition field for granodiorite is indicated in blue. upright=1.4|thumb|Mineral assemblage of igneous rocks thumb|Photomicrograph of [[thin section of granodiorite from Slovakia (in crossed polarised light)]]

Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrusions) enriched with silica and alkali metals. It is the volcanic equivalent of syenite.

thumb|right|Aplite dyke cutting Sentinel granodiorite on [[Sentinel Dome]] right|thumb|Aplite, showing fine-grained texture Aplite () is an intrusive igneous rock that has a granitic composition. Aplites are fine-grained to aphanitic (without grains visible to the naked eye) and may consist of only quartz and feldspar or the term may refer to any leucocratic (pale-coloured) minor intrusion of that grain size. They are associated with the later stages of many larger intermediate to felsic intrusions.

thumb|upright=1.3|Expanded horticultural perlite Perlite is an amorphous volcanic glass that has a relatively high water content, typically formed by the hydration of obsidian. It occurs naturally and has the unusual property of greatly expanding when heated sufficiently. It is an industrial mineral, suitable "as ceramic flux to lower the sintering temperature", and a commercial product useful for its low density after processing. It is also used as a soil conditioner in horticulture.

thumb|A piece of tonalite on red granite gneiss from Tjörn, Sweden thumb|QAPF diagram with tonalite field highlighted Tonalite is an igneous, plutonic (intrusive) rock, of felsic composition, with phaneritic (coarse-grained) texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with alkali feldspar making up less than 10% of the total feldspar content. Quartz (SiO2) is present as more than 20% of the total quartz-alkali feldspar-plagioclase-feldspathoid (QAPF) content of the rock. Amphiboles and biotite are common in lesser quantities, while accessory minerals include

thumb|Cerro Mackay, a mountain in Coyhaique in Chile, made of columns of adakite thumb|Closer view of the adakite columns of Cerro Mackay, Chile Adakites are volcanic rocks of intermediate to felsic composition that have geochemical characteristics of magma originally thought to have formed by partial melting of altered basalt that is subducted below volcanic arcs. Most magmas derived in subduction zones come from the mantle above the subducting plate when hydrous fluids are released from minerals that break down in the metamorphosed basalt, rise into the mantle, and initiate partial melting.