Subvolcanic rocks

thumb|False-color scanning electron microscope image of kimberlite from South Africa. [[Olivine crystals (green) are in a fine-grained matrix made up of clay minerals and carbonates (presented in blue, purple and buff colors).]]

sheet of rock formed in a fracture in a pre-existing rock body

thumb|Diabase

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|Komatiite lava at the type locality in the Komati Valley, Barberton Mountainland, South Africa, showing the distinctive "spinifex texture" formed by dendritic plates of olivine (scale shown by a hammer on the right edge of photo)

medium-grained intrusive rock

A tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock

thumb|Minette (a type of lamprophyre), from Jáchymov in the Czech Republic

thumb|Photomicrograph of [[thin section of latite (in plane polarised light)]] thumb|Photomicrograph of [[thin section of latite (in cross polarised light)]] Latite is an igneous, volcanic rock, with aphanitic-aphyric to aphyric-porphyritic texture. It is the volcanic equivalent of monzonite. Its mineral assemblage is usually alkali feldspar and plagioclase in approximately equal amounts. Quartz is less than five percent and is absent in a feldspathoid-bearing latite, and olivine is absent in a quartz-bearing latite. When quartz content is greater than five percent the rock is classified as qu

thumb|right|Sample of lamproite Lamproite is an ultrapotassic mantle-derived volcanic or subvolcanic rock. It has low CaO, Al2O3, Na2O, high K2O/Al2O3, a relatively high MgO content and extreme enrichment in incompatible elements.

thumb|The smooth texture of this basaltic [[volcanic bomb is aphanitic.]] thumb|upright=1.3|IUGS classification of aphanitic extrusive [[igneous rocks according to their relative alkali (Na2O + K2O) and silica (SiO2) weight contents. Blue area is roughly where alkaline rocks plot; yellow area where subalkaline rocks plot.]] thumb|An aphanitic volcanic sand grain, with fine-grained matrix (geology)|groundmass, as seen through a [[petrographic microscope]]

thumb|upright=1.3|Cross-polarized light microscope image of an intergrowth of quartz and alkali feldspar in a granophyre (Muskox intrusion), as seen in [[thin section (Long dimension is 1.5 mm)]] Granophyre ( ; from granite and porphyry) is a subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths such as those in the accompanying image.

rock composed mostly of alkali feldspar and plagioclase