Intermediate rocks

thumb|Diorite thumb|Orbicular diorite from Corsica (corsite) thumb|upright=1.7|QAPF diagram with dioritoid fields highlighted in yellow and diorite in red thumb|upright=1.4|Mineral assemblage of igneous rocks

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)]]

thumb|Demonstration of sound produced when phonolite is struck, Cerro de la Campana (Hermosillo, Sonora, Mexico) thumb|Lithophone made of Phonolite in Schellerhau botanic garden (Germany)

Boninite is an extrusive rock high in both magnesium and silica, thought to be usually formed in fore-arc environments, typically during the early stages of subduction. The rock is named for its occurrence in the Izu-Bonin arc south of Japan. It is characterized by extreme depletion in incompatible trace elements that are not fluid mobile (e.g., the heavy rare-earth elements plus Nb, Ta, Hf) but variable enrichment in the fluid mobile elements (e.g., Rb, Ba, K). They are found almost exclusively in the fore-arc of primitive island arcs (that is, closer to the ocean trench) and in ophiolite com

volcanic rock

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.

type of igneous rock

thumb|upright=1.35|Potassic trachybasalt from the July–August 2001 eruption of Mount Etna, Italy thumb|Satellite image of Bayuda volcanic field in Sudan where [[nepheline-rich trachybasalt lavas have been erupted during the Holocene epoch]] Trachybasalt is a volcanic rock with a composition between trachyte and basalt. It resembles basalt but has a high content of alkali metal oxides. Minerals in trachybasalt include alkali feldspar, calcic plagioclase, olivine, clinopyroxene and likely very small amounts of leucite or analcime.

thumb|upright=1.35|A cut block of trachyandesite lava from a volcano in Auvergne (region)|Auvergne, France, used as building stone, forming part of the walls of [[Clermont-Ferrand Cathedral, France]] thumb|upright=1.35|Trachyandesite is field S3 in the TAS diagram

Tephriphonolite or tephri-phonolite is a mafic to intermediate extrusive igneous rock in composition between phonotephrite and phonolite. It contains 9–14% alkali content and 48–57% silica content (see TAS diagram). Tephriphonolite is roughly equivalent to tephritic phonolite of the QAPF classification.

thumb|Benmoreite lava forms the "Dragon's Teeth" landmark on Maui, Hawaii Benmoreite is a volcanic rock of intermediate composition. It is a silica-undersaturated sodium-rich variety of trachyandesite (the other kind is latite) and belongs to the alkaline suite of igneous rocks. It was named after Ben More, a mountain on the Isle of Mull, Scotland.