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Types of Rocks

Andesite
Andesite

Andesite is a fine-grained rock that formed when the magma erupted onto the surface and crystallized quickly. Andesite and diorite have a composition that is intermediate between basalt and granite. This is because their parent magmas formed from the partial melting of a basaltic oceanic plate.

source: geology.com
image: pitt.edu
Basalt
Basalt

Basalt underlies more of Earth's surface than any other rock type. Most areas within Earth's ocean basins are underlain by basalt. Although basalt is much less common on continents, lava flows and flood basalts underlie several percent of Earth's land surface. Basalt is a very important rock.

source: geology.com
Dacite
Dacite

Dacite ( / ˈ d eɪ s aɪ t /) is an igneous, volcanic rock. It has an aphanitic to porphyritic texture and is intermediate in composition between andesite and rhyolite. The word dacite comes from Dacia, a province of the Roman Empire which lay between the Danube River and Carpathian Mountains (now modern Romania and Moldova) where the rock was first described.

Diorite
Diorite

Diorite is the name used for a group of coarse-grained igneous rocks with a composition between that of granite and basalt. It usually occurs as large intrusions, dikes, and sills within continental crust. These often form above a convergent plate boundary where an oceanic plate subducts beneath a continental plate.

source: geology.com
Dolerite (Also Called Diabase)
Dolerite (Also Called Diabase)

Diabase, also called Dolerite, fine- to medium-grained, dark gray to black intrusive igneous rock. It is extremely hard and tough and is commonly quarried for crushed stone, under the name of trap. Although not popular, it makes an excellent monumental stone and is one of the dark-coloured rocks commercially known as black granite.

image: flickr.com
Gabbro
Gabbro

Gabbro is a coarse-grained, dark-colored, intrusive igneous rock. It is usually black or dark green in color and composed mainly of the minerals plagioclase and augite. It is the most abundant rock in the deep oceanic crust.

source: geology.com
Granite
Granite

The Best-Known Igneous Rock. Granite is the best-known igneous rock. Many people recognize granite because it is the most common igneous rock found at Earth's surface and because granite is used to make many objects that we encounter in daily life.

source: geology.com
Limestone
Limestone

Limestone is not found everywhere. It only occurs in areas underlain by sedimentary rocks. Limestone is needed in other areas and is so important that buyers will pay five times the value of the stone in delivery charges so that limestone can be used in their project or process.

source: geology.com
image: dnr.mo.gov
Marble
Marble

Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite (CaCO 3) and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite.

source: geology.com
Nepheline
Nepheline

Nepheline syenite is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The rocks are mostly pale colored, grey or pink, and in general appearance they are not unlike granites, but dark green varieties are also known.

Obsidian
Obsidian

Obsidian is an igneous rock that forms when molten rock material cools so rapidly that atoms are unable to arrange themselves into a crystalline structure. It is an amorphous material known as a "mineraloid." The result is a volcanic glass with a smooth uniform texture that breaks with a conchoidal fracture (see photo).

source: geology.com
image: soil-net.com
Pegmatite
Pegmatite

Pegmatite is the host rock for many rare mineral deposits. These minerals can be commercial sources of: beryllium, bismuth, boron, cesium, lithium, molybdenum, niobium, tantalum, tin, titanium, tungsten, and many other elements.

source: geology.com
Peridotite
Peridotite

Peridotite is also found in the igneous rocks of sills and dikes. Ophiolites: An ophiolite is a large slab of oceanic crust, including part of the mantle, that has been overthrust onto continental crust at a convergent plate boundary.

source: geology.com
Quartzite
Quartzite

Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism. These conditions recrystallize the sand grains and the silica cement that binds them together.

source: geology.com
Sandstone
Sandstone

Sandstone is a sedimentary rock composed of sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains.

source: geology.com
Slate
Slate

Slate tile flooring: Slate is a durable rock that is suitable for use as flooring, stair treads, sidewalk slabs, and patio stone. It is also produced in a variety of colors that allow it to be incorporated into a variety of design projects.

source: geology.com