By: Saoirse Moloney
Three Types of Rocks
All types of rocks are composed of minerals. They are classified by their origin of formation and textures.
There are three types of rocks
- Igneous Rocks
- Sedimentary Rocks
- Formed by melting and solidification
- They are formed inside the Earth's Lithosphere
- The main types of Igneous Rocks are Intrusive and Extrusive. Intrusive Igneous rocks form inside of a volcano and have a short cooling time, causing them to have large crystals. Extrusive Igneous rocks crystallize quickly at the Earth's surface, causing them to have small crystals.
- Formed through compaction and cementing
- Commonly found at or near the Earth's surface
- The main types of Sedimentary rocks are Clastic (fragmental), Crystalline, and Bioclastic (Organic). Clastic Sedimentary rocks are made of different sized particles cemented together. Bioclastic Sedimentary rocks are formed by the accumulation of plant and rock fragments. They contain shells or plant materials. Crystalline Sedimentary rocks are deposited when chemicals in seawater precipitate and fall tot the ocean bottom.
ROCK TYPE EXAMPLES
- Diorite is an Igneous rock
- This crystal formed inside of a volcano. It formed slowly.
- The crystals are 1 mm to 10 mm in size. It has a coarse texture.
- It has a light color, low density, and it is Felsic.
- Potassium Fedspar 20%, 60% Quartz, 20% Plagioclase Fedspar, 10% Biotite Mica, and 10% Amphibole.
- Rock Salt is a Sedimentary rock
- Rock Salt is chemically formed.
- Fine to coarse crystals and a crystalline texture.
- Composed of Halite.
- Crystals from chemical precipitates and evaporates.
- Marble is a Metamorphic rock
- Non-Foliated texture
- Fine to coarse grain size.
- Composed or Calcite and/or Dolomite.
- Regional or Contact Metamorphism
- Metamorphism of Limestone or Dolostone.
The Rock Cycle
The Rock Cycle is a model showing how rocks and sediments change over time.