Rock Cycle & Types

This fine-grained, intermediate extrusive rock forms from the rapid cooling of lava in subduction zone volcanoes, composed primarily of plagioclase feldspar and amphibole, and is used locally as crushed stone. 

This dark, fine-grained, mafic extrusive rock forms from the rapid cooling of low-viscosity lava, is composed mainly of pyroxene and plagioclase feldspar, and constitutes most oceanic crust, where it's quarried for road aggregate. 

An extrusive rock that forms when gas-rich basaltic lava erupts and cools quickly, leaving bubble holes (vesicles) in its mafic pyroxene and feldspar composition, found in volcanic flows and used as lightweight aggregate. 

This light-colored, fine-grained, intermediate to felsic extrusive rock forms from viscous lava in explosive volcanoes, contains abundant plagioclase feldspar, quartz, and biotite, and is sometimes used as crushed construction aggregate. 

A dark, coarse-grained, mafic intrusive rock that forms from the slow crystallization of magma deep underground, composed of pyroxene and plagioclase feldspar, and is used as a dimension stone (often sold as "black granite") and road base. 

This light-colored, coarse-grained, felsic intrusive rock forms from the slow crystallization of silica-rich magma deep within the continental crust, mainly composed of quartz, feldspar, and mica, and is a premier material for countertops and monuments. 

A dense, dark, glassy, felsic extrusive rock that forms when high-silica lava cools extremely rapidly without forming crystals, essentially a volcanic glass of silica ($\text{SiO}_2$), found near rhyolite flows and historically used to make tools and weapons. 

An exceptionally coarse-grained, typically felsic intrusive rock that forms in the final stages of magma crystallization,  and can contain giant crystals of tourmaline, beryl, zircon, quartz, feldspar, and mica, and is an important source of economic minerals and rare earths. 

A porous, frothy, felsic extrusive rock formed during explosive eruptions when viscous lava depressurizes and solidifies mid-air, primarily composed of volcanic glass froth, found near composite volcanoes and used as a lightweight abrasive and concrete additive. 

A light-colored, fine-grained, felsic extrusive rock that forms from the rapid cooling of high-silica, viscous lava, chemically equivalent to granite but with a fine matrix of quartz and feldspar, and is used as crushed rock. 

A dark, highly vesicular, mafic extrusive rock formed during explosive eruptions of mafic lava, characterized by large, rough vesicles (bubbles) and composed of basaltic glass, found on cinder cones and used for landscaping and gas grills. 

A soft rock formed from the lithification (compaction) of volcanic ash and rock fragments (pyroclasts) after an explosive eruption, composed of fragments of glass and crystals, found in volcanic fields, and is easily carved for building construction. 

A salt-and-pepper colored, coarse-grained, intermediate plutonic intrusive rock that forms from the slow cooling of magma, composed of plagioclase feldspar and dark minerals like hornblende and biotite, and is sometimes used for paving and decorative stone. 

A dense, coarse-grained, ultramafic intrusive rock that makes up the Earth's mantle, composed almost entirely of olivine and pyroxene, rarely found at the surface but is the source rock for valuable commodities like chromium and diamonds. 

This dark, medium-grained, mafic hypabyssal rock forms from magma cooling relatively quickly in small intrusive bodies (dikes and sills), is composed of laths of plagioclase feldspar and pyroxene, found globally in tabular intrusions, and is highly valued as durable road aggregate and ballast. 

This clastic rock forms from cemented sand grains, is chiefly composed of quartz and feldspar, is found in ancient beach, river, and desert environments, and is widely used as a building stone and in making glass. 

Formed by the compaction of fine-grained mud, this clastic rock is predominantly composed of clay minerals and quartz silt, is common in lake bottoms and deep ocean basins, and is sometimes used for brick and cement production, or as an oil/gas source rock. 

This clastic rock forms as rounded pebbles and larger clasts are cemented together, is composed of a diverse mix of rock fragments, is deposited in high-energy river and beach settings, and is a component in the production of concrete. 

Similar to conglomerate but with angular clasts cemented together, this clastic rock is made of unsorted rock and mineral fragments, is found near cliffs or in fault zones, and is occasionally quarried for use as an ornamental stone. 

Primarily a biochemical rock, it forms from the accumulation of skeletal fragments, is composed mainly of the mineral calcite, is abundant in shallow, warm seas, and is an essential raw material for cement and concrete. 

This chemical rock is often a product of secondary alteration of limestone, consists mainly of the mineral dolomite, is found in ancient marine basins, and is used as an aggregate and a source of magnesium. 

This rock forms from the precipitation of silica or accumulation of siliceous plankton shells, consists of microcrystalline silica, occurs as nodules in limestone or bedded layers, and was historically used to make tools like arrowheads. 

A chemical evaporite rock, it forms from the precipitation of minerals as a body of water evaporates, consists primarily of the mineral halite ($\text{NaCl}$), is found in thick beds in former marine basins, and is commercially used for food seasoning and road de-icing. 

This chemical evaporite rock forms when a shallow body of water evaporates, consists of the mineral gypsum, is found interbedded with other evaporites, and is the main ingredient in drywall and plaster. 

An organic rock, it forms from the burial and compaction of plant matter, is primarily composed of carbon, occurs in ancient swamp deposits, and is widely used as a fossil fuel to generate electricity. 

This clastic rock forms from the lithification of silt-sized particles, is composed mainly of quartz and feldspar, is common in river floodplains and deltas, and is sometimes used as a fill material in construction. 

This clastic rock forms from the lithification of clay-sized particles, consists predominantly of clay minerals, is found in low-energy lakes and deep oceans, and is a source of clay for ceramics and pottery. 

A biochemical variety of limestone, it forms from the accumulation of microscopic calcareous skeletons, is composed almost entirely of fine-grained calcite, is found in deep marine sedimentary layers, and has been used for making writing chalk and lime. 

A biochemical limestone, it forms by the loose cementation of shell and fossil fragments, is composed primarily of calcite, is found near high-energy coastlines, and has been used locally as a building stone in coastal regions. 

This chemical rock forms from the precipitation and accumulation of iron minerals, is typically composed of hematite or limonite, is found in distinct bands or nodules within other sedimentary layers, and is a source of iron ore. 

This fine-grained, low-grade foliated rock forms from the regional metamorphism of shale, composed of fine mica and chlorite, and is used globally for roofing and flooring due to its excellent cleavage.

Formed from the low- to medium-grade regional metamorphism of slate, it is a fine-grained foliated rock with a distinctive silky sheen from microscopic mica crystals, and is occasionally used as a decorative building stone.

A medium-grade foliated rock, it develops through the regional metamorphism of shale or basalt, characterized by visible, aligned crystals of mica and sometimes garnet, making it a minor decorative stone found in major mountain belts. 

This high-grade foliated rock, commonly derived from granite or shale through intense regional metamorphism, displays characteristic light and dark bands of quartz, feldspar, and biotite, making it an excellent, durable material for countertops and building facades. 

A non-foliated rock resulting from the contact or regional metamorphism of limestone or dolostone, it consists of interlocking, recrystallized calcite crystals, and is famously used worldwide for sculpture, architecture, and luxury surfacing. 

Formed through the contact or regional metamorphism of quartz sandstone, this highly durable, non-foliated rock is composed of nearly pure, fused quartz grains, and is highly valued for construction, flagstones, and abrasives.

This fine-grained, non-foliated rock forms in small localized areas via contact metamorphism when magma bakes the surrounding country rock, containing various heat-resistant minerals like biotite and pyroxene, and is occasionally used as road aggregate. 

A weakly foliated to non-foliated rock, it forms from the low-temperature hydrothermal alteration of ultramafic rocks like peridotite, is dominated by soft serpentine minerals, and is sometimes used as a decorative stone. 

Formed by the low-grade metamorphism of mafic igneous rocks like basalt, this weakly foliated to non-foliated rock is colored by minerals like chlorite and actinolite, and is a feature of ancient volcanic terrains sometimes associated with mineral deposits. 

A soft, non-foliated rock created through the low to medium-grade metamorphism of ultramafic rocks, it is rich in the mineral talc, and is easily carved and used for heat-retaining applications like fireplace liners and carving. 

This extremely high-pressure, medium-temperature non-foliated rock forms from the deep-seated metamorphism of basalt or gabbro, characterized by red garnet and green omphacite, and is important for studying deep Earth and mantle processes.

A high-pressure, low-temperature foliated rock, it forms in subduction zones from the regional metamorphism of mafic rocks, owing its rare blue color to the presence of glaucophane, and serves as a key indicator of plate tectonic history. 

This highest-rank of coal, considered a metamorphic rock due to its transformation by heat and pressure from bituminous coal, is composed of over 90% pure carbon, and is highly prized as a clean-burning fuel source. 

A medium- to high-grade metamorphic rock, often weakly foliated, that forms from the regional metamorphism of mafic igneous rocks, it is rich in the black mineral hornblende and plagioclase feldspar, and is used as aggregate and dimension stone. 

A brittle, non-foliated rock formed by dynamic metamorphism (crushing and grinding) along a fault zone, it is composed of angular rock fragments and fine rock flour, and is a geological indicator of major fault movement.