Rock cycle & Classification

Rock cycle & Classification

Rock

A mixture of minerals and other materials

What are Minerals????

• a naturally occurring, inorganic solid with a crystal structure and definite chemical make up :

• The basic building blocks of rocks are minerals

Rock Classification

Origin – rocks are mainly classified by how they are formed

3 main types of rocks

• Igneous

• Sedimentary

• Metamorphic

Igneous rocks: forms from the cooling of molten rock (magma or lava)

• Extrusive Rock – igneous rock formed from lava that erupted onto Earth’s surface; basalt is the most common extrusive rock

• Intrusive Rock – igneous rock that formed when magma hardened beneath Earth’s surface; granite is the most common intrusive rock

• Texture – depends on the size and shape of the mineral crystals  Fine-grained – rapid cooling Glassy – rapid cooling Coarse, large, or medium grained – slow cooling; the slower magma cools, the larger the crystals

Sedimentary rock – forms when particles of other rocks or the remains of plants and animals are pressed and cemented together

• Processes that turn sediment to rock

• Weathering – breaks rock down into sediment

• Erosion – moving of sediment to a new location

• Deposition – dropping of sediment

• Compaction – presses sediment together

• Cementation – dissolved minerals crystallize and glue particles of sediment together 

Types of Sedimentary Rocks

• Clastic – a sedimentary rock that forms when rock fragments squeeze together like shale, sandstone and conglomerate

• Organic – forms when layers of plants and animals are deposited in thick layers like coal and limestone

• Chemical – form when minerals that are dissolved in a solution crystallize or from mineral deposits that are left when seas or lakes evaporate like rock salt

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Metamorphic rock – formed when an existing rock is changed by heat and/or pressure

• Foliated – grains arranged in parallel layers or bands like slate, schist and gneiss

• Nonfoliated – mineral grains are arranged randomly like marble and quartzite

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Rock Cycle

- forces inside the Earth and at the surface produce a rock cycle that builds, destroys, and changes the rock in the crust; the series of processes on and beneath Earth’s surface that slowly change rocks from one kind to another

Any rock can change into another type of rock; rocks of the same type can turn into a new rock of that type