The following is a list of rock types recognized by geologists. There is no agreed number of specific types of rock. Any unique combination of chemical composition, mineralogy, grain size, texture, or other distinguishing characteristics can describe a rock type. Additionally, different classification systems exist for each major type of rock. There are three major types of rock: igneous rock, metamorphic rock, and sedimentary rock.
Igneous rocks
Adakite – Volcanic rock type Agpaitic rock – Peralkaline igneous rock Andesite – Type of volcanic rock Alkali feldspar granite – Type of igneous rock rich in alkali feldspar Ankaramite – Type of volcanic rock - Igneous rock belonging to basalt family Anorthosite – Mafic intrusive igneous rock composed predominantly of plagioclase Aplite – Fine-grained intrusive igneous rock type similar to granite Basalt – Magnesium- and iron-rich extrusive igneous rock ʻAʻā – Molten rock expelled by a volcano during an eruptionPages displaying short descriptions of redirect targets – Basaltic lava with a crumpled appearance Pāhoehoe – Molten rock expelled by a volcano during an eruptionPages displaying short descriptions of redirect targets – Basaltic lava with a flowing, often ropy appearance Basaltic andesite – Volcanic rock that is intermediate in composition between basalt and andesite Basaltic trachyandesite – Naming system for volcanic rocksPages displaying short descriptions of redirect targets Mugearite – Volcanic rock type Shoshonite – Potassium-rich variety of basaltic trachyandesite Basanite – Type of volcanic rock Blairmorite – Rare porphyritic volcanic rock Boninite – Ultramafic extrusive rock high in both magnesium and silica Carbonatite – Igneous rock with more than 50% carbonate minerals Charnockite – Type of granite containing orthopyroxene Enderbite – Igneous rock of the charnockite series Dacite – Volcanic rock intermediate in composition between andesite and rhyolite Diabase, also known as dolerite – Type of igneous rock Diorite – Igneous rock type Napoleonite, also known as corsite – Variety of diorite with orbicular structure Dunite – Type of peridotite with at least over 90% olivine. Essexite – Igneous rock type Foidolite – Igneous rock rich in feldspathoid minerals Gabbro – Coarse-grained mafic intrusive rock Granite – Type of igneous rock Granodiorite – Type of coarse grained intrusive igneous rock Granophyre – Type of subvolcanic rock Harzburgite – Type of peridotite with less than 5% clinopyroxene and less than 90% olivine. Hornblendite – Plutonic rock consisting mainly of the amphibole hornblende Hyaloclastite – Volcanic rock consisting of glass fragments Icelandite – Igneous rock type Ignimbrite – Type of volcanic rock Ijolite – Igneous rock consisting essentially of nepheline and augite Kimberlite – Igneous rock which sometimes contains diamonds Komatiite – Magnesium-rich igneous rock Lamproite – Mantle rock expulsed to the surface in volcanic pipes Lamprophyre – Type of ultrapotassic igneous rock – An ultramafic, ultrapotassic intrusive rock dominated by mafic phenocrysts in a feldspar groundmass Latite – Type of volcanic rock – A silica-undersaturated form of andesite Leucitite Lherzolite – Type of igneous rock – An ultramafic rock, essentially a peridotite Monzodiorite An intrusive igneous rock intermediate in composition between diorite and monzonite Monzogabbro – Type of intrusive igneous rock Monzogranite – Biotite granite rocks that are considered to be the final fractionation product of magma – 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-bearing diorite – Form of intrusive igneous rock Nepheline syenite – Holocrystalline plutonic rock – A silica-undersaturated plutonic rock of nepheline and alkali feldspar Nephelinite – Igneous rock made up almost entirely of nepheline and clinopyroxene – A silica-undersaturated plutonic rock with >90% nepheline Norite – Mafic intrusive igneous rock – A hypersthene-bearing gabbro Obsidian – Naturally occurring volcanic glass Pegmatite – Igneous rock with very large interlocked crystals Peridotite – Coarse-grained ultramafic igneous rock Phonolite – Uncommon extrusive rock – A silica-undersaturated volcanic rock; essentially similar to nepheline syenite Phonotephrite – A volcanic rock with a composition between phonolite and tephrite Picrite – Variety of high-magnesium basalt that is very rich in the mineral olivinePages displaying short descriptions of redirect targets – An olivine-bearing basalt Porphyry – Textural form of igneous rock with large grained crystals in a fine matrix Pumice – Volcanic rock Pyroxenite – Ultramafic igneous rock composed of pyroxene minerals - a coarse grained plutonic rock composed of >90% pyroxene Quartz diorite – Igneous, plutonic rock – A diorite with >5% modal quartz Quartz monzonite – Type of igneous rock – An intermediate plutonic rock, essentially a monzonite with 5–10% modal quartz Quartzolite – Extremely rare igneous rock made mostly of quartz – An intrusive rock composed mostly of quartz Rhyodacite – Volcanic rock rich in silica and low in alkali metal oxides – A felsic volcanic rock which is intermediate between a rhyolite and a dacite Rhyolite – Igneous, volcanic rock, of felsic (silica-rich) composition Comendite – Hard, peralkaline igneous rock, a type of light blue grey rhyolite Pantellerite – Peralkaline rhyolite type of volcanic rock Scoria – Dark vesicular volcanic rock Shonkinite – Intrusive igneous rock – a plutonic rock Sovite – Igneous rock – A coarse-grained carbonatite rock Syenite – Intrusive igneous rock – A plutonic rock dominated by orthoclase feldspar; a type of granitoid Syenogranite – Intrusive igneous rock of the granite family Tachylyte – Form of basaltic volcanic glassPages displaying short descriptions of redirect targets – Essentially a basaltic glass Tephriphonolite – Type of igneous rock – A volcanic rock with a composition between phonotephrite and phonolite Tephrite – Igneous, volcanic rock – A silica-undersaturated volcanic rock Tonalite – Igneous rock – A plagioclase-dominant granitoid Trachyandesite – Extrusive igneous rock – An alkaline intermediate volcanic rock Benmoreite – Volcanic rock type - sodic trachyandesite Trachybasalt – Volcanic rock – A volcanic rock with a composition between basalt and trachyte Hawaiite – Volcanic rock – a sodic type of trachybasalt, typically formed by ocean island (hot spot) volcanism Trachyte – Extrusive igneous rock – A silica-undersaturated volcanic rock; essentially a feldspathoid-bearing rhyolite Troctolite – Igneous rock – A plutonic ultramafic rock containing olivine, pyroxene and plagioclase Trondhjemite – Light-colored intrusive igneous rock – A form of tonalite where plagioclase-group feldspar is oligoclase Tuff – Rock consolidated from volcanic ash Vitrophyre – Glassy volcanic rock - Glassy igneous rock with phenocrysts Websterite – Pyroxenite with clino and orthopyroxene – A type of pyroxenite, composed of clinopyroxene and orthopyroxene Wehrlite – Ultramafic rock - An ultramafic plutonic or cumulate rock, a type of peridotite, composed of olivine and clinopyroxene
Sedimentary rocks
Argillite – Sedimentary rock, mostly of indurated clay particles Arkose – Type of sandstone containing at least 25% feldspar Banded iron formation – Layered iron-rich sedimentary rock Breccia – Rock composed of angular fragments Calcarenite – Type of limestone that is composed predominantly of sand-size grains Chalk – Soft carbonate rock Chert – Hard, fine-grained sedimentary rock composed of cryptocrystalline silica Claystone – Clastic sedimentary rock composed primarily of clay-sized particles Coal – Combustible sedimentary rock composed primarily of carbon Conglomerate – Sedimentary rock composed of smaller rock fragments Coquina – Sedimentary rock that is composed mostly of fragments of shells Diamictite – Type of sedimentary rock Diatomite – Soft, siliceous sedimentary rock that is easily crumbled Dolomite (rock), also known as Dolostone – Sedimentary carbonate rock containing a high percentage of the mineral dolomite Evaporite – Water-soluble mineral deposit formed by evaporation from an aqueous solution Flint – Cryptocrystalline form of the mineral quartz Geyserite – Form of opaline silica often found around hot springs and geysers Greywacke – Sandstone with angular grains in a clay-fine matrix Gritstone – Hard, coarse-grained, siliceous sandstone Ironstone – Sedimentary rock that contains a substantial proportion of iron ore Itacolumite – Porous sandstone known for flexibility Jaspillite – Banded mixture of hematite and quartz Laterite – Product of rock weathering in wet tropical climates rich in iron and aluminium Lignite – Soft, brown, combustible, sedimentary rock Limestone – Type of sedimentary rock 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 Phosphorite – Sedimentary rock containing large amounts of phosphate minerals – A non-detrital sedimentary rock that contains high amounts of phosphate minerals Sandstone – Type of sedimentary rock Shale – Fine-grained, clastic sedimentary rock Siltstone – Sedimentary rock which has a grain size in the silt range Sylvinite – Sedimentary rock made of a mechanical mixture of sylvite and halite Tillite – Till which has been indurated or lithified by burial Travertine – Form of limestone deposited by mineral springs Tufa – Porous variety of limestone rock Turbidite – Geologic deposit of a turbidity current Wackestone – Mud-supported carbonate rock that contains greater than 10% grains
Metamorphic rocks
Anthracite – Hard, compact variety of coal Amphibolite – Metamorphic rock type Blueschist – Type of metavolcanic rock Cataclasite – Rock found at geological faults – A rock formed by faulting Eclogite – Metamorphic rock formed under high pressure Gneiss – Common high-grade metamorphic rock Granulite – Class of high-grade medium to coarse grained metamorphic rocks Greenschist – Metamorphic rock – A mafic metamorphic rock dominated by green amphiboles Hornfels – Group of metamorphic rocks Calcflinta – Calc-silicate hornfels Jadeitite – Metamorphic rock found in blueschist-grade metamorphic terranes Litchfieldite – Igneous rock – Nepheline syenite gneiss Marble – Type of metamorphic rock – a metamorphosed limestone Migmatite – Mixture of metamorphic rock and igneous rock Mylonite – Metamorphic rock – A metamorphic rock formed by shearing Metaconglomerate - A type of metamorphic rock formed through the recrystallization of conglomerates Metapelite – Metamorphic rockPages displaying short descriptions of redirect targets – 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 – Type of foliated metamorphic rock – A low grade metamorphic rock composed mostly of micaceous minerals Pseudotachylite – Glassy or very fine-grained type of rockPages displaying short descriptions of redirect targets – A glass formed by melting within a fault via friction Quartzite – Hard, non-foliated metamorphic rock – A metamorphosed sandstone typically composed of >95% quartz Schist – Easily split medium-grained metamorphic rock Semipelite – Metamorphic rockPages displaying short descriptions of redirect targets – that falls between pelitic (clay-rich) and psammitic (sand-rich) compositions Serpentinite – Rock formed by transformation of olivine Skarn – Hard, coarse-grained, hydrothermally altered metamorphic rocks Slate – Metamorphic rock - A low grade metamorphic rock formed from shale or silt Suevite – Rock consisting partly of melted material formed during an impact event – 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 Soapstone – Talc-bearing metamorphic rock – Essentially a talc schist Tectonite – Rock whose structure reflects its history of deformation Whiteschist – Type of metamorphic rock – A high pressure metamorphic rock containing talc and kyanite
Specific varieties 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.
Adamellite – Type of igneous rockPages displaying short descriptions of redirect targets – A variety of quartz monzonite Appinite – Type of igneous rock – A group of varieties of lamprophyre, mostly rich in hornblende Aphanite – Igneous rock composed of very small crystals invisible to the naked eye Borolanite – Variety of nepheline syenite from Loch Borralan, Scotland – A variety of nepheline syenite from Loch Borralan, Scotland Blue Granite – Variety of monzonite, an igneous rock Epidosite – Hydrothermally altered epidote- and quartz-bearing rock Felsite – Very fine-grained volcanic rock that sometimes contains larger crystals Flint – Cryptocrystalline form of the mineral quartz Ganister – Hard, fine-grained quartzose sandstone, or orthoquartzite Gossan – Intensely oxidized, weathered or decomposed rock Hyaloclastite – Volcanic rock consisting of glass fragments Ijolite – Igneous rock consisting essentially of nepheline and augite Jadeitite – Metamorphic rock found in blueschist-grade metamorphic terranes Jasperoid – Type of rock – A hematite-silica metasomatite analogous to a skarn Kenyte – Type of igneous rock - A variety of phonolite, first found on Mount Kenya Lapis lazuli – Metamorphic rock containing lazurite, prized for its intense blue color - A rock composed of lazurite and other minerals Larvikite – Variety of monzonite, an igneous rock Listwanite – Metamorphic rock Litchfieldite – Igneous rock – A metamorphosed nepheline syenite occurrence near Litchfield, Maine Llanite – Type of rock – A hypabyssal rhyolite with microcline and blue quartz phenocrysts from the Llano Uplift in Texas Luxullianite – Rare type of granite Mangerite – Plutonic intrusive igneous rock, that is essentially a hypersthene-bearing monzonite Minette (ore) – Type of iron ore found in the south of Luxembourg and in Lorraine – A variety of lamprophyre Novaculite – Type of rock – A type of chert found in Oklahoma, Arkansas, and Texas Pietersite – Variety of chalcedony Pyrolite – Model composition of the Earth's mantle – A chemical analogue considered to theoretically represent the Earth's upper mantle Rapakivi granite – Type of igneous rock Rhomb porphyry – Textural form of igneous rock with large grained crystals in a fine matrixPages displaying short descriptions of redirect targets – A type of latite with euhedral rhombic phenocrysts of feldspar Rodingite – Metamorphic rock – A mafic rock metasomatized by serpentinization fluids Shonkinite – Intrusive igneous rock – melitilic and kalsititic rocks Taconite – Variety of iron-bearing sedimentary rock Tachylite – Form of basaltic volcanic glass Teschenite – Type of igneous rock – A silica undersaturated, analcime bearing gabbro Theralite – Igneous rock – A nepheline gabbro Unakite – Multicoloured metamorphic rock – An altered granite Variolite – Igneous rocks which contain varioles Vogesite – Type of ultrapotassic igneous rock – A variety of lamprophyre Wad (mineral) – Porous secondary manganese oxyhydroxide – A rock rich in manganese oxide or manganese hydroxide
See also
List of minerals List of rocks on Mars Rock cycle – Transitional concept of geologic time List of rock formations: for a list of unusual or culturally significant rock outcrops Leaverite – Rock in the field that looks interesting but is actually not
References
External links British Geological Survey rock classification scheme Igneous rock classification Archived 2005-08-29 at the Wayback Machine Rock Types Article by Encyclopædia Britannica Classification of common rocks and soils Metamorphic Rock Classification Volcanic rocks Earth Science Education Unit virtual rock kit