Rock Formation and the Rock Cycle

Study Notes

Rocks are aggregates of minerals, which may or may not contain organic matter.
The geosphere is constructed of various types of rocks.
The rock cycle is a model illustrating the formation, breakdown, and transformation of rocks into different types.
Any type of rock can serve as a raw material for another.

Igneous Rocks: Formed from the cooling of molten magma. Can be categorized into:
- Intrusive Igneous Rocks: Form in Earth’s interior with slow cooling, creating larger crystals.
- Extrusive Igneous Rocks: Form on Earth's surface with rapid cooling, resulting in smaller crystals.
Sedimentary Rocks: Formed from the accumulation of pre-existing rocks and organic fossils.
Metamorphic Rocks: Formed from existing rocks subjected to heat and pressure.

Cooling of magma or lava leads to the formation of igneous rocks.
Quenching: Rapid cooling of molten rock creates a glassy texture, exemplified by volcanic glass like obsidian.
Igneous rocks are grouped based on mineral content:
- Felsic (Granitic) Rocks: Light-colored minerals.
- Basaltic (Mafic) Rocks: Dark gray to black minerals.

Weathering: Breaks down rocks into smaller fragments, occurring physically or chemically.
Erosion: Transports unconsolidated materials through natural agents such as wind, water, and organisms.
Deposition: Settlement of materials in one location.
Lithification: Process where sediments turn into sedimentary rocks through compaction and cementation.

Classified based on foliation, which refers to the orientation of mineral grains.
Two types exist:
- Foliated Metamorphic Rocks: Show clear layers formed under stress, typically near plate boundaries.
- Non-foliated Metamorphic Rocks: Lack distinct layers, forming in areas of minimal deformation.

Rocks are aggregates of minerals and can be categorized as igneous, sedimentary, or metamorphic based on their formation processes.
The rock cycle emphasizes the interrelationship between different rock types.
Ice and snowflakes are debated as minerals due to their crystalline structure and natural occurrence.

Defined as naturally occurring, inorganic solids with a definite chemical composition and ordered crystalline structure.
Physical properties of minerals include:
- Color: Determined by light wavelengths reflected.
- Streak: The color of a mineral in powdered form.
- Luster: The appearance or sheen of a mineral's surface.