Rocks and Their Importance

Importance of Rocks

• Fundamental components of the Earth, formed from aggregates of minerals.
• Source of fuel:
  • Petroleum products derived from sedimentary rocks include oil, coal, and natural gas.
• Used as construction materials:
  • Granite and sandstone are quarried for infrastructure projects such as roads, bridges, and buildings.
• Tourist attractions:
  • Natural landmarks like the Grand Canyon National Park draw visitors due to their unique rock formations.
• Provide food and nutrients:
  • Rock salts (sodium chloride) sourced from sedimentary rocks contribute to human diets.
• Essential for soil formation:
  • Physical and chemical weathering of rocks creates soil, vital for agriculture and food production.

Types of Rocks

• Igneous Rocks:

  • Formed from the solidification of magma, containing various mineral deposits.
  • Typically do not react to acids, with mineral deposits presenting in patchy forms.
  • Subtypes:
    • Intrusive Igneous Rocks (Plutonic): Formed within the Earth's crust, characterized by slow cooling and coarse texture.
    • Extrusive Igneous Rocks (Volcanic): Formed at or near the Earth’s surface, resulting from rapid cooling, exhibiting fine or glassy texture.

• Sedimentary Rocks:

  • Composed of lithified sediments or remains of living organisms.
  • Formed through a series of processes including weathering, erosion, deposition, burial, compaction, and cementation.
  • Occupy about 75% of the Earth's crust, typically layered (strata).

• Metamorphic Rocks:

  • Result from the transformation of existing rocks under high heat and pressure (metamorphism).
  • May exhibit foliation (banding) and can vary in color from light to dark.

Minerals

• Naturally occurring inorganic substances with specific chemical compositions and physical properties.
• Serve as components of rocks and crucial materials for various industries.

Mineral Extraction

• Rocks and minerals mined for processing into everyday products.
• Ore: A deposit that is economically viable for extraction.
• Extraction methods:
  • Surface Mining: Utilized when ore is accessible near the Earth's surface, employs open-pit, quarry, or strip mining.
  • Subsurface Mining: Required for deeper ore deposits, involves digging horizontal or angled tunnels; commonly extracts iron, coal, and salt.

Environmental Consequences of Mineral Extraction

• Groundwater and surface water contamination harming water quality essential for communities.
• Instability from collapsed tunnels posing safety risks to miners.
• Landscape destruction associated with methods like strip or pit mining, affecting ecosystems.
• Air pollution resulting from mineral extraction processes and waste materials (slag).