Rocks and Minerals Quiz

Rocks and Minerals

• Minerals are naturally occurring, homogeneous solids with specific chemical compositions and highly ordered atomic structures. They have specific physical properties.
• Crystals are solids with three-dimensional plane faces.
• Mineral properties for identification:
  • Color: Least reliable, some minerals have similar colors.
  • Streak: Color of a mineral in powdered form (more reliable). Halite and quartz are minerals that are difficult to distinguish by color alone
  • Hardness: Resistance to scratching (Mohs Hardness Scale).
    • Mohs Hardness Scale lists minerals from hardest to softest. Diamond is the hardest, and talc is the softest.
  • Cleavage/Fracture: How a mineral breaks.
    • Cleavage: Breaks along smooth, flat surfaces (mica).
    • Fracture: Breaks along irregular surfaces (quartz).
    • Quartz is a transparent gemstone with conchoidal fracture and is relatively brittle.

Properties of Minerals

• Gypsum can be scratched by a copper penny.
• Talc is the softest mineral and can be scratched by a fingernail.
• Luster describes how a mineral reflects light.
• Specific gravity (density) is the weight of a mineral compared to the weight of water.

Rocks

• Rocks are aggregates of minerals or rock fragments.
• Types of rocks:
  • Igneous: Formed from cooled magma or lava.
    • Lava is magma that reaches the Earth's surface.
  • Sedimentary: Formed from the remains of once-living organisms (fossils) or compacted sediment.
  • Metamorphic: Formed by heat and pressure changing existing rocks.

Rock Cycle

• The rock cycle describes the continuous processes that transform rocks from one type to another.

Endogenic and Exogenic Processes

• Endogenic processes occur below the Earth's surface and are driven by heat and gravity.
• Exogenic processes occur at or near the Earth's surface and are driven by forces like water, wind, and ice. Examples include faulting, solidification, weathering, mudflows, mass wasting, and erosion.