List of rock types

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.^[1] There are three major types of rock: igneous rock, metamorphic rock, and sedimentary rock.

Igneous rocks

A sample of andesite (dark groundmass) with amygdaloidal vesicles filled with zeolite. Diameter of view is 8 cm.

Adakite
Andesite – Type of volcanic rock
Alkali feldspar granite – Type of igneous rock rich in alkali feldspar
Anorthosite – Mafic intrusive igneous rock composed predominantly of plagioclase
Aplite
Basalt – Magnesium- and iron-rich extrusive igneous rock
- ʻAʻā – Basaltic lava with a crumpled appearance
- Pāhoehoe – Basaltic lava with a flowing, often ropy appearance
Basaltic trachyandesite
- Mugearite
- Shoshonite
Basanite – Type of volcanic rock
Blairmorite
Boninite
Carbonatite
Charnockite
- Enderbite
Dacite – Volcanic rock intermediate in composition between andesite and rhyolite
Diabase, also known as dolerite
Diorite
- Napoleonite, also known as corsite
Dunite – Ultramafic and ultrabasic rock from Earth's mantle which is made of the mineral 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 – Subvolcanic rock that contains quartz and alkali feldspar in characteristic angular intergrowths
Harzburgite
Hornblendite
Hyaloclastite
Icelandite – Igneous rock type
Ignimbrite
Ijolite
Kimberlite – Igneous rock which sometimes contains diamonds
Komatiite – Magnesium-rich igneous rock
Lamproite
Lamprophyre – An ultramafic, ultrapotassic intrusive rock dominated by mafic phenocrysts in a feldspar groundmass
Latite – Type of volcanic rock – 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 – Igneous rock with very large interlocked crystals
Peridotite
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 olivine – An olivine-bearing basalt
Porphyry – Textural form of igneous rock with large grained crystals in a fine matrix
Pumice – Extremely vesicular volcanic rock, typically light-colored
Pyroxenite - a coarse grained plutonic rock composed of >90% pyroxene
Quartz diorite – 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
Scoria
Shonkinite – Intrusive igneous rock – a plutonic rock
Sovite – A coarse-grained carbonatite rock
Syenite – Intrusive igneous rock – A plutonic rock dominated by orthoclase feldspar; a type of granitoid
Tachylyte – 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 – An alkaline intermediate volcanic rock
- Benmoreite - 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 – A plutonic ultramafic rock containing olivine, pyroxene and plagioclase
Trondhjemite – A form of tonalite where plagioclase-group feldspar is oligoclase
Tuff – Rock consolidated from volcanic ash
Websterite – Ultramafic and ultrabasic rock – 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 rocks

Bituminous coal seam in West Virginia

Limey shale overlaid by limestone. Cumberland Plateau, Tennessee

Dolomite crystals from Touissite, Morocco

Turbidite (Gorgoglione Flysch), Miocene, South Italy

Argillite – Sedimentary rock, mostly of indurated clay particles
Arkose
Banded iron formation – Distinctive layered units of iron-rich sedimentary rock that are almost always of Precambrian age
Breccia – Rock composed of angular fragments
Calcarenite
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
Diamictite
Diatomite – Soft, siliceous sedimentary rock that is easily crumbled
Dolomite (rock), also known as Dolostone
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
Gritstone – Hard, coarse-grained, siliceous sandstone
Itacolumite
Jaspillite
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
Oil shale – Organic-rich fine-grained sedimentary rock containing kerogen
Oolite
Phosphorite – A non-detrital sedimentary rock that contains high amounts of phosphate minerals
Sandstone – Type of sedimentary rock
Shale – Fine-grained, clastic sedimentary rock
Siltstone
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
Turbidite – Geologic deposit of a turbidity current
Wackestone – Mud-supported carbonate rock that contains greater than 10% grains

Metamorphic rocks

Phyllite

Banded gneiss with a dike of granite orthogneiss

Marble

Quartzite

Manhattan Schist, from Southeastern New York

Slate

Anthracite – Hard, compact variety of coal
Amphibolite – Metamorphic rock type
Blueschist
Cataclasite – Rock found at geological faults – A rock formed by faulting
Eclogite
Gneiss – Common high-grade metamorphic rock
Granulite
Greenschist – Metamorphic rock – A mafic metamorphic rock dominated by green amphiboles
Hornfels
- Calcflinta – A type of hornfels found in the Scottish Highlands
Litchfieldite – Nepheline syenite gneiss
Marble – Type of metamorphic rock – a metamorphosed limestone
Migmatite – Mixture of metamorphic rock and igneous rock
Mylonite – A metamorphic rock formed by shearing
Metapelite – Metamorphic rock – 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 – A glass formed by melting within a fault via friction
Quartzite – A metamorphosed sandstone typically composed of >95% quartz
Schist – Easily split medium-grained metamorphic rock
Serpentinite
Skarn
Slate – Metamorphic rock - A low grade metamorphic rock formed from shale or silts
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 type – A rock whose fabric reflects the history of its 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 – 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 – A variety of nepheline syenite from Loch Borralan, Scotland
Blue Granite – Variety of monzonite, an igneous rock
Epidosite
Felsite
Flint – Cryptocrystalline form of the mineral quartz
Ganister
Gossan – Intensely oxidized, weathered or decomposed rock
Hyaloclastite
Ijolite
Jadeitite – Metamorphic rock found in blueschist-grade metamorphic terranes
Jasperoid – 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
Litchfieldite – A metamorphosed nepheline syenite occurrence near Litchfield, Maine
Llanite – A hypabyssal rhyolite with microcline and blue quartz phenocrysts from the Llano Uplift in Texas
Luxullianite
Mangerite – Plutonic intrusive igneous rock, that is essentially a hypersthene-bearing monzonite
Minette – A variety of lamprophyre
Novaculite – Type of rock – A type of chert found in Oklahoma, Arkansas, and Texas
Pietersite – Commercial term for a variety of chalcedony
Pyrolite – 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 matrix – A type of latite with euhedral rhombic phenocrysts of feldspar
Rodingite – A mafic rock metasomatized by serpentinization fluids
Shonkinite – Intrusive igneous rock – melitilic and kalsititic rocks
Taconite
Tachylite
Teschenite – Type of igneous rock – A silica undersaturated, analcime bearing gabbro
Theralite – Igneous rock – A nepheline gabbro
Unakite – An altered granite
Variolite
Vogesite – A variety of lamprophyre
Wad (mineral) – Porous secondary manganese oxyhydroxide – A rock rich in manganese oxide or manganese hydroxide

References

^ "BGS Rock Classification Scheme - Igneous - Metamorphic - Sedimentary - Superficial". British Geological Survey (BGS). Retrieved 2019-05-28.

External links

[BGS_Rock_Classification_Scheme_-_Igneous_-_Metamorphic_-_Sedimentary_-_Superficial-1] "BGS Rock Classification Scheme - Igneous - Metamorphic - Sedimentary - Superficial". British Geological Survey (BGS). Retrieved 2019-05-28.

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