Part 1
Where do minerals come from?
Inorganic Crystallization: Atoms arrange into crystals. Ex. Lava/magma forms into quartz, feldspar, and biotite when it cools and hardens.
Recrystallization: Minerals form and reform in water. Ex. Rock salt/limestone precipitates on the bottom of a warm shallow sea.
Characteristics of Igneous Rocks (See ERST Pg 6)
1. Intrusive/Plutonic: Form underground from magma.
2. Extrusive/Volcanic: Form on/near the surface when lava cools.
3. Texture: Describes the crystal/grain size, and the grain size depends on the cooling time.
Clastic (Fragmental)
Contains rock fragments, and is classified by grain size.
What ate Metamorphic Rocks?
Changed rocks, meta=change morph=form, and is caused by heat and/or pressure.
Rock-Forming Minerals and Silicates
There are over 2000 known materials, 20-30 are the most common and found in many rocks.
All minerals that contain the elements Si and O, make up to 90% of the Earth's crust, and the structure is the silicon and oxygen tetrahedron.
Mafic vs Felsic
Mafic: Dark-colored, High % of Fe and Mg, High density.
Felsic: Light-colored, High % of Al and silica (Si and O), low density.
Clastic (Fragmental)
Contains rock fragments, and is classified by grain size.
Evidence of Metamorphism
Distorted structure, high density and hardness, and partial melting and re-crysallization.
Composition of the Earth's Crust
According to the ERST Pg 11 and the graph above, the most abundant elements int eh Earth's crust are: 1st Oxygen 2nd Silicon
Silicates = Si + O
Crystalline
Sed. Rocks that form when minerals precipitate in water, and Evaporation and Precipitation.
Types of Metamorphism
Regional: Heat and pressure over a large area.
Contact: Change due to direct contact with magma/lava.
Mineral Properties
1. Color: Helpful but is not enough to identify a mineral.
2. Streak: Powdered form in color.
3. Luster: Way the mineral reflects light.
4. Hardness: Resistance to being scratched.
5. Cleavage: Flat breakage pattern due to the atomic arrangement.
6. Fracture: Rough breakage pattern due to the atomic arrangement.
7. Carbonate Test: Reaction to acid, mineral includes CO3
8. Composition: Elements in a mineral
Bioclastic/ Organic Sedimentary Rocks
Fragmental rock that contains evidence of life, Rocks made from something that used to be alive and includes fossiliferous rocks.
Texture of Metamorphic Rocks
Foliated: Show bending/mineral alignment, Regional only.
Nonfoliated: No banding, forms by contact, and, or regional Metamorphism.