Rocks: Types, Characteristics, and Uses
Rocks
Igneous Rocks
Igneous rocks are formed when magma or lava cools and solidifies. They can be classified into two main types: intrusive and extrusive.
Intrusive Igneous Rocks
Intrusive igneous rocks are formed when magma cools and solidifies slowly beneath the Earth’s surface. They are typically coarse-grained and have a crystalline texture.
Granite
Granite is a common intrusive igneous rock. It is composed of quartz, feldspar, and mica. Granite is a hard and durable rock that is often used for building and construction.
Serpentine
Serpentine is a type of intrusive igneous rock that is composed of magnesium silicate. It is a soft and slippery rock that is often used for decorative purposes.
Extrusive Igneous Rocks
Extrusive igneous rocks are formed when lava cools and solidifies quickly on the Earth’s surface. They are typically fine-grained and have a glassy or porphyritic texture.
Obsidian
Obsidian is a type of extrusive igneous rock that is composed of volcanic glass. It is a hard and brittle rock that is often used for making tools and weapons.
Pumice
Pumice is a type of extrusive igneous rock that is composed of volcanic foam. It is a lightweight and porous rock that is often used for insulation and abrasives.
Basalt
Basalt is a type of extrusive igneous rock that is composed of pyroxene and feldspar. It is a dark and dense rock that is often used for road construction and building.
Sedimentary Rocks
Sedimentary rocks are formed when sediments, such as sand, mud, and gravel, are compacted and cemented together. They can be classified into three main types: clastic, chemical, and organic.
Clastic Sedimentary Rocks
Clastic sedimentary rocks are formed when fragments of other rocks are compacted and cemented together. They can be further classified into two types: conglomerate and sandstone.
Conglomerate
Conglomerate is a type of clastic sedimentary rock that is composed of rounded fragments of other rocks. It is a hard and durable rock that is often used for building and construction.
Sandstone
Sandstone is a type of clastic sedimentary rock that is composed of sand grains. It is a soft and porous rock that is often used for building and construction.
Chemical Sedimentary Rocks
Chemical sedimentary rocks are formed when minerals precipitate out of water. They can be further classified into two types: limestone and dolomite.
Limestone
Limestone is a type of chemical sedimentary rock that is composed of calcium carbonate. It is a soft and porous rock that is often used for building and construction.
Dolomite
Dolomite is a type of chemical sedimentary rock that is composed of calcium magnesium carbonate. It is a hard and durable rock that is often used for building and construction.
Organic Sedimentary Rocks
Organic sedimentary rocks are formed when the remains of plants and animals are compacted and cemented together. They can be further classified into two types: coal and oil shale.
Coal
Coal is a type of organic sedimentary rock that is composed of the remains of plants. It is a black or brown rock that is often used for fuel.
Oil shale
Oil shale is a type of organic sedimentary rock that is composed of the remains of algae. It is a black or brown rock that is often used for producing oil.
Metamorphic Rocks
Metamorphic rocks are formed when existing rocks are subjected to heat and pressure. They can be classified into three main types: foliated, non-foliated, and cataclastic.
Foliated Metamorphic Rocks
Foliated metamorphic rocks are characterized by the presence of parallel layers or bands. They can be further classified into two types: schist and gneiss.
Schist
Schist is a type of foliated metamorphic rock that is composed of mica and other minerals. It is a soft and flaky rock that is often used for roofing and flooring.
Gneiss
Gneiss is a type of foliated metamorphic rock that is composed of quartz, feldspar, and mica. It is a hard and durable rock that is often used for building and construction.
Non-Foliated Metamorphic Rocks
Non-foliated metamorphic rocks do not have a layered or banded structure. They can be further classified into two types: marble and quartzite.
Marble
Marble is a type of non-foliated metamorphic rock that is composed of calcite. It is a soft and durable rock that is often used for building and construction.
Quartzite
Quartzite is a type of non-foliated metamorphic rock that is composed of quartz. It is a hard and durable rock that is often used for building and construction.
Cataclastic Metamorphic Rocks
Cataclastic metamorphic rocks are formed when rocks are subjected to intense shearing or crushing. They are typically characterized by a fine-grained and brecciated texture.
Breccia
Breccia is a type of cataclastic metamorphic rock that is composed of broken fragments of other rocks. It is a hard and durable rock that is often used for building and construction.
Mylonite
Mylonite is a type of cataclastic metamorphic rock that is composed of fine-grained minerals. It is a soft and slippery rock that is often used for making pottery and tiles.