List of rock types

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The following is a list of rock types recognized by geologists. There is no agreed number of specific types of rocks. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe rock types. Additionally, different classification systems exist for each major type of rock.[citation needed] There are three major types of rock: igneous, sedimentary, and metamorphic. They are all identified by their texture, streak, and location, among other factors.

Igneous[edit]

A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm.
  • Adakite – A class of intermediate to felsic volcanic rocks containing low amounts of yttrium and ytterbium
  • Andesite – An intermediate volcanic rock
  • Alkali feldspar granite – A granitoid in which at least 90% of the total feldspar is alkali feldspar
  • Anorthosite – A mafic intrusive igneous rock composed predominantly of plagioclase
  • Aplite – A fine-grained intrusive igneous rock type similar to granite
  • Basalt – A magnesium- and iron-rich extrusive igneous rock
    • A'a - basaltic lava with a crumpled appearance
    • Pahoehoe - basaltic lava with a flowing, often ropy appearance
  • Basaltic trachyandesite
    • Mugearite – Oligoclase-bearing basalt, comprising olivine, apatite, and opaque oxides
    • Shoshonite – A potassium-rich variety of basaltic trachyandesite
  • Basanite – A silica-undersaturated basalt
  • Blairmorite – Rare porphyritic volcanic rock
  • Boninite – Utramafic extrusive rock high in both magnesium and silica
  • Carbonatite – Igneous rock with more than 50% carbonate minerals
  • Charnockite – A type of granite containing orthopyroxene
    • Enderbite – An igneous rock of the charnockite series
  • Dacite – Volcanic rock intermediate in composition between andesite and rhyolite
  • Diabase, also known as dolerite – An intrusive mafic rock forming dykes or sills
  • Diorite – Intermediate intrusive igneous rock composed principally of plagioclase feldspar
    • Napoleonite, also known as corsite – A variety of diorite with orbicular structure
  • Dunite – An ultramafic and ultrabasic rock from Earth's mantle and made of the mineral olivine.
  • Essexite – a dark gray or black holocrystalline plutonic rock
  • Foidolite – A rare coarse-grained intrusive igneous rock in which more than 60% of light-coloured minerals are feldspathoids
  • Gabbro – A coarse-grained mafic intrusive rock
  • Granite – A common type of intrusive, felsic, igneous rock with granular structure
  • Granodiorite – A phaneritic-textured intrusive igneous rock similar to granite
  • Granophyre – A subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths
  • Harzburgite – An ultramafic and ultrabasic mantle rock. Found in ophiolites.
  • Hornblendite – Plutonic rock consisting mainly of the amphibole hornblende
  • Hyaloclastite – A volcaniclastic accumulation or breccia
  • Icelandite – An iron rich, aluminium poor andesite
  • Ignimbrite – A variety of hardened tuff
  • Ijolite – An igneous rock consisting essentially of nepheline and augite
  • Kimberlite – An igneous rock which sometimes contains diamonds
  • Komatiite – An ultramafic mantle-derived volcanic rock
  • Lamproite – Ultrapotassic mantle-derived volcanic or subvolcanic rock
  • Lamprophyre - an ultramafic, ultrapotassic intrusive rock dominated by mafic phenocrysts in a feldspar groundmass
  • Latite - a silica-undersaturated form of andesite
  • Lherzolite - an ultramafic rock, essentially a peridotite
  • Monzogranite - a silica-undersaturated granite with <5% normative quartz
  • Monzonite – Igneous intrusive rock with low quartz and equal plagioclase and alkali feldspar - a plutonic rock with <5% normative quartz
  • Nepheline syenite - a silica-undersaturated plutonic rock of nepheline and alkali feldspar
  • Nephelinite - a silica-undersaturated plutonic rock with >90% nepheline
  • Norite - a hypersthene-bearing gabbro
  • Obsidian – Naturally occurring volcanic glass
  • Pegmatite – Very coarse grained plutonic rock
  • Peridotite – A coarse-grained ultramafic igneous rock
  • Phonolite - a silica-undersaturated volcanic rock; essentially similar to nepheline syenite
  • Phonotephrite - a volcanic rock with a composition between phonolite and tephrite
  • Picrite - an olivine-bearing basalt
  • Porphyry – Textural form of igneous rock with large grained crystals in a fine matrix
  • Pumice – Light coloured highly vesicular volcanic glass
  • Pyroxenite - a coarse grained plutonic rock composed of >90% pyroxene
  • Quartz diorite - a diorite with >5% modal quartz
  • Quartz monzonite - an intermediate plutonic rock, essentially a monzonite with 5-10% modal quartz
  • Quartzolite - an intrusive rock composed mostly of quartz
  • Rhyodacite - a felsic volcanic rock which is intermediate between a rhyolite and a dacite
  • Rhyolite – An igneous, volcanic rock, of felsic (silica-rich) composition
    • Comendite – A hard, peralkaline igneous rock, a type of light blue grey rhyolite
    • Pantellerite – A peralkaline rhyolite type of volcanic rock
  • Scoria – Dark vesicular volcanic rock
  • Sovite - a coarse-grained carbonatite rock
  • Syenite - a plutonic rock dominated by orthoclase feldspar; a type of granitoid
  • Tachylyte - essentially a basaltic glass
  • Tephriphonolite - a volcanic rock with a composition between phonotephrite and phonolite
  • Tephrite - a silica-undersaturated volcanic rock
  • Tonalite - a plagioclase-dominant granitoid
  • Trachyandesite - an alkaline intermediate volcanic rock
    • Benmoreite – A silica-undersaturated volcanic rock of intermediate composition - sodic trachyandesite
  • Trachybasalt - a volcanic rock with a composition between basalt and trachyte
  • Trachyte - a silica-undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite
  • Troctolite - a plutonic ultramafic rock containing olivine, pyroxene and plagioclase
  • Trondhjemite – A light-colored intrusive igneous rock - a form of tonalite where plagioclase-group feldspar is oligoclase
  • Tuff – Rock consolidated from volcanic ash
  • Websterite - a type of pyroxenite, composed of clinoproxene and orthopyroxene
  • Wehrlite - an ultramafic plutonic or cumulate rock, a type of peridotite, composed of olivine and clinopyroxene

Sedimentary[edit]

Bituminous coal seam in West Virginia
Dolomite crystals from Touissite, Morocco
Turbidite (Gorgoglione Flysch), Miocene, South Italy
  • Argillite – Sedimentary rock, mostly of indurated clay particles
  • Arkose – A type of sandstone containing at least 25% feldspar
  • Banded iron formation – Distinctive layered units of iron-rich sedimentary rock that are almost always of Precambrian age
  • Breccia – Rock composed of broken fragments cemented by a matrix
  • Calcarenite – A type of limestone that is composed predominantly of sand-size grains
  • Chalk – A soft, white, porous sedimentary rock made of calcium carbonate
  • Chert – A hard, fine-grained sedimentary rock composed of crystals of quartz (silica) that are very small
  • Claystone – Clastic sedimentary rock composed primarily of clay-sized particles
  • Coal – A combustible sedimentary rock composed primarily of carbon
  • Conglomerate – A coarse-grained clastic sedimentary rock with mainly rounded to subangular clasts
  • Coquina – A sedimentary rock that is composed mostly of fragments of shells
  • Diamictite – A lithified sedimentary rock of non- to poorly sorted terrigenous sediment in a matrix of mudstone or sandstone
  • Diatomite – Naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder
  • Dolostone, also known as Dolomite – Sedimentary carbonate rock that contains a high percentage of the mineral dolomite
  • Evaporite – A water-soluble mineral sediment formed by evaporation from an aqueous solution
  • Flint – Cryptocrystalline form of the mineral quartz
  • Geyserite – A form of opaline silica that is often found around hot springs and geysers
  • Greywacke – A hard, dark sandstone with poorly sorted angular grains in a compact, clay-fine matrix
  • Gritstone – A hard, coarse-grained, siliceous sandstone
  • Itacolumite – A porous, yellow sandstone that is flexible when cut into thin strips
  • Jaspillite – A banded mixture of hematite and quartz
  • Laterite – A soil and rock type rich in iron and aluminium
  • Lignite – A soft, brown, combustible, sedimentary rock
  • Limestone – Sedimentary rocks made of calcium carbonate
  • Marl – Lime-rich mud or mudstone which contains variable amounts of clays and silt
  • Mudstone – Fine grained sedimentary rock whose original constituents were clays or muds
  • Oil shale – Organic-rich fine-grained sedimentary rock containing kerogen
  • Oolite – Sedimentary rock formed from ooids
  • Sandstone – A clastic sedimentary rock composed mostly of sand-sized particles
  • Shale – A fine-grained, clastic sedimentary rock
  • Siltstone – Sedimentary rock which has a grain size in the silt range
  • Sylvinite – A sedimentary rock made of a mechanical mixture of sylvite and halite
  • Tillite – Till which has been indurated or lithified by burial
  • Travertine – A form of limestone deposited by mineral springs
  • Tufa – Porous limestone rock formed when carbonate minerals precipitate out of ambient temperature water
  • Turbidite – The geologic deposit of a turbidity current
  • Wackestone – A mud-supported carbonate rock that contains greater than 10% grains

Metamorphic[edit]

Phyllite
Banded gneiss with a dike of granite orthogneiss
Marble
Quartzite
Manhattan Schist, from Southeastern New York
Slate
  • Anthracite – A hard, compact variety of coal that has a submetallic luster
  • Amphibolite – A metamorphic rock containing mainly amphibole and plagioclase - a metamorphic rock composed primarily of amphibole
  • Blueschist – A metavolcanic rock that forms by the metamorphism of basalt and rocks with similar composition
  • Cataclasite – Rock formed by fracturing and comminution during faulting - a rock formed by faulting
  • Eclogite – A dense, mafic metamorphic rock
  • Gneiss – A common high-grade metamorphic rock
  • Granulite – A class of high-grade medium to coarse grained metamorphic rocks
  • Greenschist - a mafic metamorphic rock dominated by green amphiboles
  • Hornfels – A series of contact metamorphic rocks that have been baked and indurated by the heat of intrusive igneous masses
  • Litchfieldite - nepheline syenite gneiss
  • Marble - a metamorphosed limestone
  • Migmatite – A mixture of metamorphic rock and igneous rock
  • Mylonite - a metamorphic rock formed by shearing
  • Metapelite - a metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock
  • Metapsammite - a metamorphic rock with a protolith of quartz-rich (sandstone) sedimentary rock
  • Phyllite - a low grade metamorphic rock composed mostly of micaceous minerals
  • Pseudotachylite - a glass formed by melting within a fault via friction
  • Quartzite - a metamorphosed sandstone typically composed of >95% quartz
  • Schist – Medium grade metamorphic rock with lamellar grain
  • Serpentinite – Hydration and metamorphic transformation of igneous rock
  • Skarn – Hard, coarse-grained, hydrothermally altered metamorphic rocks
  • Slate – A fine-grained, foliated, homogeneous, weakly metamorphic rock - a low grade metamorphic rock formed from shale or silts
  • Suevite - a rock formed by partial melting during a meteorite impact
  • Talc carbonate - a metamorphosed ultramafic rock with talc as an essential constituent; similar to a serpentinite
  • Whiteschist - a high pressure metamorphic rock containing talc and kyanite

Specific varieties of rocks[edit]

The following are terms for rocks that are not petrographically or genetically distinct but are defined according to various other criteria; most are specific classes of other rocks, or altered versions of existing rocks. Some archaic and vernacular terms for rocks are also included.

See also[edit]

  • List of minerals – A list of minerals for which there are articles on Wikipedia
  • List of rocks on Mars – Alphabetical list of named rocks and meteorites found on Mars
  • Rock cycle – Transitions through geologic time among the three main rock types: sedimentary, metamorphic, and igneous
  • List of rock formations: for a list of unusual or culturally significant rock outcrops.
  • Leaverite – A specimen in the field that may look interesting but is actually not

External links[edit]