List of rock types

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This page is intended as a list of all unique rock types as recognised by petrologists. Names of non-rock types and archaic rock types are given as appendices.

Contents

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Top of page — See also — External links

[edit] A

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

Amphibolite - a metamorphic rock composed primarily of amphibole

Epidiorite

Andesite - an Intermediate volcanic rock

Anorthosite - an igneous ultramafic rock composed predominantly of plagioclase

Anthracite - a type of coal

Aplite - a very fine grained intrusive igneous rock

Argillite - a sedimentary rock composed primarily of clay-sized particles

Arkose - a sedimentary rock similar to sandstone

[edit] B

Banded iron formation - a fine grained chemical sedimentary rock composed of iron oxide minerals

Basalt - a volcanic rock of mafic composition

Adakite - a class of basaltic rocks containing relatively small amounts of the trace elements 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

Blueschist - a metamorphic rock composed of sodic amphiboles with a distinct blue colour

Boninite - a high-magnesian basalt dominated by pyroxene

Breccia - a sedimentary or tectonic rock composed of fragments of other, broken rocks

[edit] C

Bituminous coal seam in West Virginia

Carbonatite - a rare igneous rock composed of >50% carbonate minerals

Cataclasite - a rock formed by faulting

Chalk - a sedimentary rock composed primarily of coccolith fossils

Charnockite - a rare type of granite containing pyroxene

Enderbite - a variety of charnockite

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

[edit] D

Dolomite crystals from Touissite, Morocco

Dacite - a felsic to intermediate volcanic rock with high iron content

Diabase or dolerite - an intrusive mafic rock forming dykes or sills

Diatomite - a sedimentary rock fromed from diatom fossils

Diorite - a coarse grained intermediate plutonic rock composed of plagioclase, pyroxene and/or amphibole

Dolomite or dolostone - a carbonate rock composed of the mineral dolomite +/- calcite

Dunite - an ultramafic cumulate rock composed of olivine and accessories

[edit] E

Eclogite - an ultra-high grade metamorphosed basalt or gabbro; also a facies of metamorphic rocks

Essexite - a silica undersaturated mafic plutonic rock (essentially a foid-bearing gabbro)

Evaporite - a chemical sedimentary rock formed by accumulation of minerals after evaporation

[edit] F

Flint - a form of chert

Foidolite - a plutonic igneous rock composed of >90% feldspathoid minerals

Banded gneiss with a dike of granite orthogneiss

[edit] G

Gabbro - a coarse grained plutonic rock composed of pyroxene and plagioclase basically equivalent to basalt

Gneiss - a coarse grained metamorphic rock

Gossan - the product of the weathering of a sulfide rock or ore body

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

Granulite - a high grade metamorphic rock formed from basalt; also a facies of metamorphic rocks

Greywacke - an immature sandstone with quartz, feldspar and rock fragments within a clay matrix

Greenschist - a generic term for a mafic metamorphic rock dominated by green amphiboles

Greenstone

Gritstone - essentially a coarse sandstone formed from small pebbles

[edit] H

Harzburgite - a variety of peridotite; an ultramafic cumulate rock

Hornblendite - a mafic or ultramafic cumulate rock dominated by >90% hornblende

Hornfels - a metamorphic rock formed by heating by an igneous rock

Hyaloclastite - a volcanic rock composed primarily of glasses and glassy tuff

[edit] I

Icelandite - a volcanic rock

Ignimbrite - a fragmental volcanic rock

Ijolite - a very rare silica-undersaturated plutonic rock

Limey shale overlaid by limestone. Cumberland Plateau, Tennessee

[edit] J

Jaspillite - an iron-rich chemical sedimentary rock similar to chert or banded iron formation

[edit] K

Kimberlite - a rare ultramafic, ultrapotassic volcanic rock and a source of diamonds

Komatiite - an ancient ultramafic volcanic rock

[edit] L

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

Lignite - a sedimentary rock composed of organic material; otherwise known as Brown Coal

Limestone - a sedimentary rock composed primarily of carbonate minerals

Marble

[edit] M

Marble - a metamorphosed limestone

Marl - a limestone with a considerable proportion of silicate material

Migmatite - a high grade metamorphic rock verging upon melting into a magma

Monzogranite - a silica undersaturated granite with <5% normative quartz

Monzonite - a plutonic rock with <5% normative quartz

Mudstone - a sedimentary rock composed of clay and muds

Mylonite - a metamorphic rock formed by shearing

[edit] N

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

[edit] O

Phyllite

Obsidian - a type of volcanic glass

Oil shale - a sedimentary rock composed dominantly of organic material

Oolite - a chemical sedimentary limestone

[edit] P

Pegmatite - a metamorphic or igneous rock with giant sized crystals

Pelite - a metamorphic rock with a protolith of clay-rich (siltstone) sedimentary rock

Peridotite - a plutonic or cumulate ultramafic rock composed of >90% olivine

Phonolite - a silica undersaturated volcanic rock; essentially similar to nepheline syenite

Phyllite - a low grade metamorphic rock composed mostly of micaceous minerals

Picrite - an olivine-bearing basalt

Quartzite

Porphyry - a rock, usually granitic, with a porphyritic texture

Psammite - a metamorphic rock with a protolith of quartz-rich (sandstone) sedimentary rock

Pseudotachylite - a glass formed by melting within a fault via friction

Pumice - a fine grained, extremely vesicular volcanic rock

Pyroxenite - a coarse grained plutonic rock composed of >90% pyroxene

[edit] Q

Quartzite - a metamorphosed sandstone typically composed of >95% quartz

Quartz diorite - a diorite with >5% modal quartz

Quartz monzonite - an intermediate plutonic rock, essentially a monzonite with 5-10% modal quartz

[edit] R

Manhattan Schist, from Southeastern New York

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

[edit] S

Sandstone - a clastic sedimentary rock defined by its grain size

Schist - a low to medium grade metamorphic rock

Scoria - an extremely vesicular mafic volcanic rock

Serpentinite - a metamorphosed ultramafic rock dominated by serpentine minerals

Shale - a clastic sedimentary rock defined by its grain size

Siltstone - a clastic sedimentary rock defined by its grain size

Skarn - a metasomatic rock

Slate

Slate - a low grade metamorphic rock formed from shale or silts

Sovite - a coarse grained carbonatite rock

Suevite - a rock formed by partial melting during a meteorite impact

Syenite - a plutonic rock dominated by orthoclase feldspar; a type of granitoid

[edit] T

Talc carbonate - a metamorphosed ultramafic rock with talc as an essential constituent; similar to a serpentinite

Soapstone - essentially a talc schist

Tachylyte - essentially a basaltic glass

Tephrite - a silica undersaturated volcanic rock; can be a generic term

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

Turbidite (Gorgoglione Flysch), Miocene, South Italy

Trondhjemite - a form of tonalite where plagioclase-group feldspar is oligoclase

Tuff - a fine grained volcanic rock formed from volcanic ash

Turbidite - a particular sequence of sedimentary rocks which form within the deep ocean environment

[edit] W

Wackestone - a matrix-supported carbonate sedimentary rock

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

[edit] Z

Contents

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Top of page — See also — External links

[edit] Specific Varieties of Rocks

The following terms are used to describe rocks which 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 analagous to a skarn