Rocks
By: Taylor Hackett
What is a rock?
Igneous Rocks
**Where they are formed: Igneous rocks are formed in and outside of volcanoes
**Two types of Igneous Rocks:
*Intrusive Rocks: are rocks that crystallizes SLOWLY inside the earth's crust
*Extrusive Rocks: are rocks that crystallizes QUICKLY at earth's surface.
Sedimentary Rocks
**Where they are formed: Sedimentary rocks are formed on the earth's surface.
**Three types of Sedimentary Rocks:
*Clastic (Fragmental) Sedimentary Rocks: are rocks that are made of different sized particles cemented together.
*Bioclastic (Organic) Sedimentary Rocks: are rocks formed by the accumulation of plant and animal remains.
* Crystalline Sedimentary Rocks: are rocks that are deposited when chemicals in seawater precipitate and fall to the ocean bottom.
Metamorphic Rocks
**Where they are formed: Metamorphic rocks are formed deep (up to 20 km) within the earth.
**Two types of Metamorphic Rocks:
*Regional Metamorphism: large masses of rock changed by deep burial within earth.
*Contact Metamorphism: chemical and physical change to a rock caused by nearby intrusion or extrusion of molten rock.
Rock Type Examples
Granite
*Texture: Coarse
*Crystal Size: 1 mm- 10 mm
*Non-vesicular
*Color-Lighter
*Density-Lower
*Composition-Felsic
*Percent of each mineral present:
- 20% of Potassium Feldspar
- 40% of Quatrz
- 20% of Plagioclase Feldspar
- 10% of Biotite
- 10% of Amphibole
Sandstone
*Texture: Clastic (fragmental)
*Grain Size: Sand( 0.006 to 0.2 cm)
*Composition: Mostly quartz, feldspar, and clay minerals; may contain fragments of other rocks and minerals
*Comments: Fine to Coarse
Phyllite
*Grain Size: Fine to Medium
*Composition: Mica, Quartz, Feldspar, Amphibole, and Garnet
*Type of Metamorphism: Regional (Heat and Pressure increases)
*Comments: Foliation surfaces shiny from microscopic mica crystals.