A list of all unique
rock types recognized by petrologists. Names of non-rock types and archaic rock types are given as appendices. Igneous [edit ]
A sample of andesite (dark groundmass) with
vesicules filled with
. Diameter of view is 8 cm.
Andesite - an Intermediate volcanic rock Anorthosite - an intrusive igneous felsic rock composed predominantly of plagioclase Aplite - a very fine grained intrusive igneous rock composed of quartz and feldspar Basalt - a volcanic rock of mafic composition Adakite - a class of basaltic rocks containing low yttrium and ytterbium Hawaiite - a class of basalts formed from ocean island ( hot spot) magmatism. Basanite - a volcanic rock of mafic composition; essentially a silica undersaturated basalt Boninite - a high-magnesian basalt dominated by pyroxene Carbonatite - a rare igneous rock composed of >50% carbonate minerals Charnockite - a type of granite containing pyroxene Enderbite - a variety of charnockite Dacite - a felsic to intermediate volcanic rock with high iron content Diabase or dolerite - an intrusive mafic rock forming dykes or sills Diorite - a coarse grained intermediate plutonic rock composed of plagioclase, pyroxene and/or amphibole Dunite - a phaneritic ultramafic rock composed of more than 90% olivine, usually forsteritic Essexite - a silica undersaturated mafic plutonic rock (essentially a foid-bearing gabbro) Foidolite - a plutonic igneous rock composed of >90% feldspathoid minerals Gabbro - a coarse grained plutonic rock composed of pyroxene and plagioclase basically equivalent to basalt Granite - a coarse grained plutonic rock composed of orthoclase, plagioclase and quartz Granodiorite - a granitic plutonic rock with plagioclase > orthoclase Granophyre - a subvolcanic intrusive rock of granitic composition Harzburgite - a variety of peridotite; an ultramafic cumulate rock Hornblendite - a mafic or ultramafic cumulate rock dominated by >90% hornblende Hyaloclastite - a volcanic rock composed primarily of glasses and glassy tuff Icelandite - a volcanic rock Ignimbrite - a fragmental volcanic rock Ijolite - a very rare silica-undersaturated plutonic rock Kimberlite - a rare ultramafic, ultrapotassic volcanic rock and a source of diamonds Komatiite - an ancient ultramafic volcanic rock Lamproite - an ultrapotassic volcanic 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 - a plutonic rock with <5% normative quartz Nepheline syenite - a silica undersaturated plutonic rock with nepheline replacing orthoclase Nephelinite - a silica undersaturated plutonic rock with >90% nepheline Norite - a hypersthene bearing gabbro Obsidian - a type of volcanic glass Pegmatite - an igneous rock (or metamorphic rock) with giant sized crystals Peridotite - a plutonic or cumulate ultramafic rock composed of olivine and pyroxene Phonolite - a silica undersaturated volcanic rock; essentially similar to nepheline syenite Picrite - an olivine-bearing basalt Porphyry - a rock, usually granitic, with a porphyritic texture Pumice - a fine grained, extremely vesicular volcanic rock 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 Rhyodacite - a felsic volcanic rock which is intermediate between a rhyolite and a dacite Rhyolite - a felsic volcanic rock Comendite - a peralkaline rhyolite Pantellerite - an alkaline rhyolite-rhyodacite with amphibole phenocrysts Scoria - an extremely vesicular mafic 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 Tephrite - a silica undersaturated volcanic rock Tonalite - a plagioclase-dominant granitoid Trachyandesite - an alkaline intermediate volcanic rock Benmoreite - sodic trachyandesite Basaltic trachyandesite Mugearite - sodic basaltic trachyandesite Shoshonite - potassic basaltic trachyandesite Trachyte - 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 - a fine grained volcanic rock formed 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 ]
Dolomite crystals from Touissite, Morocco
Turbidite (Gorgoglione Flysch), Miocene, South Italy
Argillite - a sedimentary rock composed primarily of clay-sized particles Arkose - a sedimentary rock similar to sandstone Banded iron formation - a fine grained chemical sedimentary rock composed of iron oxide minerals Breccia - a sedimentary or tectonic rock composed of fragments of other, broken rocks Chalk - a sedimentary rock composed primarily of coccolith fossils Chert - a fine grained chemical sedimentary rock composed of silica Claystone - a sedimentary rock formed from clay Coal - a sedimentary rock formed from organic matter Conglomerate - a sedimentary rock composed of large rounded fragments of other rocks Diamictite - a poorly sorted conglomerate Coquina - a sedimentary carbonate rock formed by accumulation of abundant shell fossils and fragments Diatomite - a sedimentary rock formed from diatom fossils Dolomite or dolostone - a carbonate rock composed of the mineral dolomite +/- calcite Evaporite - a chemical sedimentary rock formed by accumulation of minerals after evaporation Flint - a form of chert Greywacke - an immature sandstone with quartz, feldspar and rock fragments within a clay matrix Gritstone - essentially a coarse sandstone formed from small pebbles Itacolumite - porous, yellow sandstone Jaspillite - an iron-rich chemical sedimentary rock similar to chert or banded iron formation Laterite - a residual sedimentary rock formed from a parent rock under tropical conditions Lignite - a sedimentary rock composed of organic material; otherwise known as Brown Coal Limestone - a sedimentary rock composed primarily of carbonate minerals Marl - a limestone with a considerable proportion of silicate material Mudstone - a sedimentary rock composed of clay and muds Oil shale - a sedimentary rock composed dominantly of organic material Oolite - a chemical sedimentary limestone Rock Gypsum- Sandstone - a clastic sedimentary rock defined by its grain size Shale - a clastic sedimentary rock defined by its grain size Siltstone - a clastic sedimentary rock defined by its grain size Travertine - a sedimentary rock containing calcite and iron oxides Turbidite - a particular sequence of sedimentary rocks which form within the deep ocean environment Wackestone - a matrix-supported carbonate sedimentary rock. Metamorphic [edit ]
Banded gneiss with a
of granite orthogneiss
Manhattan Schist, from Southeastern New York
Anthracite - a type of coal Amphibolite - a metamorphic rock composed primarily of amphibole Blueschist - a metamorphic rock composed of sodic amphiboles with a distinct blue color Cataclasite - a rock formed by faulting Eclogite - an ultra-high grade metamorphosed basalt or gabbro; also a facies of metamorphic rocks Gneiss - a coarse grained metamorphic rock Gossan - the product of the weathering of a sulfide rock or ore body Granulite - a high grade metamorphic rock formed from basalt; also a facies of metamorphic rocks Greenschist - a mafic metamorphic rock dominated by green amphiboles Greenstone Hornfels - a metamorphic rock formed by heating by an igneous rock Marble - a metamorphosed limestone Migmatite - a high grade metamorphic rock verging upon melting into a magma Mylonite - a metamorphic rock formed by shearing Metapelite - a metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock Phyllite - a low grade metamorphic rock composed mostly of micaceous minerals Metapsammite - a metamorphic rock with a protolith of quartz-rich (sandstone) sedimentary rock Pseudotachylite - a glass formed by melting within a fault via friction Quartzite - a metamorphosed sandstone typically composed of >95% quartz Schist - a low to medium grade metamorphic rock Serpentinite - a metamorphosed ultramafic rock dominated by serpentine minerals Skarn - a metasomatic rock Slate - 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 Soapstone - essentially a talc schist Whiteschist - a high pressure metamorphic rock containing talc + 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.
Adamellite - a variety of quartz monzonite Appinite - a group of varieties of lamprophyre, mostly rich in hornblende Aphanite - an aphanitic felsic volcanic rock which confounds identification via optical means Borolanite - a variety of nepheline syenite from Loch Borralan, Scotland Blue Granite - essentially larvikite, a monzonite Epidosite - a type of metasomatite; essentially altered basalt Felsite - an aphanitic felsic volcanic rock which confounds identification via optical means Flint - typically a form of chert, jasper, or tuff Ganister - a Cornish term for a palaeosol formed on sandstone Ijolite - a silica- undersaturated plutonic rock associated with nepheline syenites Jadeitite - a very rare rock formed by concentration of jadeite pyroxene; a form of serpentinite Jasperoid - a hematite-silica metasomatite analogous to a skarn Kenyte - a variety of phonolite, first found on Mount Kenya Vogesite - a variety of lamprophyre Larvikite - a variety of monzonite with microperthitic ternary feldspars from Larvik, Norway Litchfieldite - a metamorphosed nepheline syenite occurrence near Litchfield, Maine Luxullianite - a tourmaline-bearing granite with a peculiar texture, occurring at Luxulyan, Cornwall, England Mangerite - a hypersthene-bearing monzonite Minette - a variety of lamprophyre Novaculite - a chert formation found in Oklahoma, Arkansas and Texas Pyrolite - a chemical analogue considered to theoretically represent the earth's upper mantle Rapakivi granite - a granite which exhibits the peculiar rapakivi texture Rhomb porphyry - a type of latite with euhedral rhombic phenocrysts of feldspar Shonkinite - melitilic and kalsititic rocks Taconite - banded iron formation, primarily used in the United States of America Teschenite - essentially a silica undersaturated, analcime bearing gabbro Theralite - essentially a nepheline gabbro Variolite - devitrified glass See also [edit ] External links [edit ]