Physical Geology 101
Rocks and the Rock Cycle
Rock
A solid, natural, cohesive aggregate of one or more minerals, mineraloids, glass, biologic particles or rock fragments
Solid
Natural
Cohesive Aggregate
What holds all of the particles together?
Interlocking mineral grains as minerals grow they form a three dimensional interlocking matrix.
Cementation - other minerals can grow between the grains cementing the grains together - calcite, quartz, iron oxide, halite
Compaction due to increased pressure
Aggregate
One or more:
minerals:
mineraloids:
glass:
biologic particles:
rock fragments:
Rock Forming Minerals
Minerals commonly found in rocks
• Feldspars: Plagioclase, Orthoclase
• Quartz
• Micas: Biotite, Muscovite, and Chlorite
• Amphibole - Hornblende
• Pyroxene - Augite
• Olivine
• Carbonates - Calcite, Dolomite
• Clay minerals
Minerals and Rocks
A naturally occurring, inorganic solid with a definite chemical composition and a regular internal crystalline structure
A solid, natural, cohesive aggregate of one or more minerals, mineraloids, glass, biologic particles or rock fragments
Rock Identification
Rocks are identified based on two main criteria:
Composition
Chemical composition
Types of particles that comprise the rock
Biologic material
Texture
Not a measure of roughness or smoothness of a rock
Overall appearance of a rock
- large crystals vs. small crystals
- layering vs. no layers
Rock Types
Igneous Rocks
Sedimentary Rocks
Metamorphic Rocks
Rock Cycle