Types of Rocks List

A rock refers to a solid accumulation of minerals situated in the lithosphere. Generally, rocks are classified into metamorphic, igneous and sedimentary rocks. The classifications are based on their textural, mineral and chemical composition. Here is a list of the types of rocks.

There Are Basically 3 Types of Rocks

  1. Igneous
  2. Sedimentary
  3. Metamorphic
Beyond these three types of rocks, each type has many rock types classified underneath them.

Types of Igneous Rocks

These rocks are formed from molten magma which cools down and splits into types; volcanic and plutonic rocks. Plutonic rocks are formed when magma cools down and crystallizes in the earth’s crust. On the other hand, volcanic rocks are created when magma reaches the earth’s surface as fragmental ejectiles or lava.

Andesite – A volcanic rock
Anorthosite – A plutonic igneous felsic rock
Aplite – A fine grained plutonic igneous rock
Basalt – A mafic composed volcanic rock
Basanite – A mafic composed volcanic rock
Boninite – Extremely high-magnesian basalt
Carbonatite – A very rare igneous rock
Charnockite –  A granite containing pyroxene
Enderbite – A type of charnockite
Dacite – High iron content intermediate volcanic
Diabase or Dolerite – A plutonic mafic rock
Diorite – Coarse grained intermediate intrusive rock
Dunite – Ultramafic rock
Essexite – Undersaturated mafic intrusive rock
Foidolite – An intrusive igneous rock
Gabbro – Coarse grained intrusive rock
Granite – Coarse grained intrusive rock
Granodiorite – Granitic intrusive rock
Granophyre – An intrusive rock
Harzburgite – A type of peridotite
Hornblendite – An ultramafic cumulate rock
Hyaloclastite – A type of volcanic rock
Icelandite – Volcanic rock
Ignimbrite – Volcanic rock
Ijolite – A rare silica plutonic rock
Kimberlite – A very rare ultramafic volcanic rock
Komatiite – An ultramafic volcanic rock
Lamproite – A volcanic rock
Lamprophyre – An ultrapotassic intrusive rock
Lherzolite – A peridotite
Monzogranite – A silica granite
Monzonite – An intrusive rock
Nepheline syenite – An undersaturated plutonic rock
Nephelinite – An undersaturated plutonic rock
Obsidian – A volcanic glass
Pegmatite – A type of igneous rock with huge sized crystals
Peridotite – A plutonic ultramafic rock
Phonolite – An undersaturated volcanic rock
Picrite – A basalt with olivine
Porphyry – A porphyritic textured rock
Pumice – A very fine grained volcanic rock
Pyroxenite – Coarse grained intrusive rock
Quartz diorite – A diorite
Quartz monzonite – An intrusive plutonic rock
Rhyodacite – An intermediate felsic volcanic rock
Rhyolite – A volcanic rock
Scoria – Mafic volcanic rock
Sovite – Coarse grained rock
Syenite – An intrusive plutonic rock
Tachylyte – A basaltic glass
Tephrite – An undersaturated volcanic rock
Tonalite – A granitoid
Trondhjemite – A type of tonalite
Trachyte – An undersaturated volcanic rock
Troctolite – An intrusive ultramafic rock
Tuff – A very fine grained volcanic rock
Websterite – A kind of pyroxenite
Wehrlite – A cumulate rock

Types of Sedimentary Rocks

The formation of sedimentary rocks results from the sedimentation of materials within water bodies and in the earth’s surface. Although they spread extensively over the crust, they constitute only 5 percent of the earth’s crust volume.

Argillite – Composed of clay-sized particles
Arkose – A rock similar to sandstone
Banded iron formation – A very fine grained sedimentary rock
Breccia – Consists of fragments of other rocks
Chalk – Composed of coccolith fossils
Chert – A very fine grained sedimentary rock
Claystone – Formed from clay
Coal – Created from organic matter
Conglomerate – Consist of big rounded fragments
Coquina – Created by accumulation of a lot of shell fossils
Diatomite – Created from diatom fossils
Dolomite or dolostone – Composed of the dolomite mineral
Evaporite – Created by mineral accumulation after evaporation
Flint – A kind of chert
Greywacke – sandstone with quartz and feldspar
Gritstone – Created from small pebbles
Itacolumite – Yellow sandstone
Jaspillite – A high-iron content chemical sedimentary rock
Laterite – Formed from parent rocks
Lignite – Created from organic materials
Limestone – Composed of carbonate minerals
Marl – A limestone with silicate material
Mudstone – Composed of muds and clay
Oil shale – Composed of organic materials
Oolite – A sedimentary limestone
Sandstone – Defined by the grain size
Travertine – Contains iron oxides and calcite
Turbidite – Form in deep oceanic environment

Types of Metamorphic Rocks

These rocks are formed when rocks undergo changes (metamorphosis) due to pressure and heat. The type of existing rock which undergoes changes is known as protolith. Sedimentary and igneous rocks often undergo this process to become metamorphic rocks.

Anthracite – Coal
Amphibolite – Composed of amphibole
Blueschist – Consist of sodic amphiboles
Cataclasite – Formed by faulting
Eclogite – A high grade metamorphosed gabbro or basalt
Gossan – Formed due to weathering of sulfide rocks
Granulite – Formed from basalt
Greenschist – Characterized by green amphiboles
Hornfels – Created by heating from an igneous rock
Marble – A limestone
Mylonite – Formed by shearing
Phyllite – Composed of micaceous minerals
Pseudotachylite – Formed by melting
Quartzite – Composed of quartz
Serpentinite – Composed of serpentine minerals
Slate – Formed from silts or shale
Suevite – Created by partial melting

Although rocks are classified into metamorphic rocks, igneous rocks and sedimentary rocks, there are no major differences between them. Their constituent mineral changes and various situations may cause them to change to the other.

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