What are rocks?
A rock is a mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underlying the soils or oceans.
- They are formed by the cooling and crystalization of molten rock
- They are formed outside or near a volcano
- They main types are extrusive and intrusive
- Extrusive rocks form outside the volcano and cool quickly which produces small crystals
- Intrusive rocks form inside the volcano and cools slowly which produces large crystals.
- Sedimentary rocks form from compaction and cementation of sediments.
- Sedimentary rocks are formed at or near the Earth's surface
- The three main types are Clastic, Bioclastic, and Crystalline
- Clasticic are rocks that are made up of different sized particles that are cemented together
- Bioclastic are rocks formed by the accumulation of plant and animal remains and contain shell or plant material
- Crystalline are rocks that are deposited when chemicals in sea water precipitate and fall to the ocean floor
- They form when other rocks are exposed to heat and/or pressure without melting
- (melting->magma->igneous rock)
- Metamorphic rocks are formed deep within the Earth
- The two main types of metamorphic rocks are folliated and non-folliated
- Folliated rocks contains a wavy alignment of crystals
- Non-folliated rocks have no wavy alignment of crystals
- Cooled slowly and formed inside the volcano
- Very coarse
- crystal size- 10 mm or larger
- Light colored
- Low density
- 30% Potassium feldspar,30% Quartz, 25% Plagioclase feldspar,15% Amphibole, and 10% Biotite
- Chemically and/or organically formed
- Bioclastic or Crystalline
- Composed of Calcite
- Precipitates of biologic origin or cemented shelll fragments
- The rock cycle is a model that shows how rocks and sediments change overtime
- It shows the external processes that occur on earth's surface
- It also shows the internal processes that occur within the earth