The Rock-etts
By;Cynthia
Rocks for Dummies
Rocks are composed of minerals.Minerals are inorganic substances with a definite chemical composition.They may also be inorganic which are formed by living organisms.Rocks are classified by their origin. There are three types of rocks.
1. Igneous
2.Metamorphic
3.Sedimentary
Igneous Rocks
- Are found in (intrusive) or outside of (extrusive) volcanoes
- Are formed by melting and solidification (cooling)
- It's texture consists of a glassy surface,Inter connected crystals,and vesicles (holes).
Metamorphic
- Are found deep below the earth's surface
- Are formed by intense heat and pressure
- It's texture consists of foliation (bands) or non-foliation.
Sedimentary
- Are found on the earth's surface
- Are formed by Cementing and compaction (pressure).
- Sedimentary rocks usually contain fossils,cemented and compacted shells and or sediments.
Pegmatite
*Igneous Rock*
- Its an intrusive Rock
- Its crystal size is 10 mm and up
- Its texture is very coarse and non-vesicular
Shale
*Sedimentary Rock*
- Compact and may easily split
- Its composition is mostly quartz,feldspar,and clay minerals;may contain fragments of other rocks and minerals
- Its grain size is clay (less than 0.0004 cm)
- Its texture consists of clastic (fragmental)
Gneiss
*Metamorphic Rock*
- High-grade metamorphism mineral types segregated into bands
- Its type of metamorphism is regional (heat and pressure increase).
- Its composition is Mica,Quartz,Feldspar,Amphibole,Garnet,and Pyroxene
- Its grain size is medium to coarse
- Its Texture consists of foliation
The Rock Cycle
The rock cycle is a model showing the relationship as to how rocks and sediments change over time.