Earth's Structure and Processes

Crust: Minerals

• Minerals are naturally occurring, inorganic, uniform materials that have definite chemical and physical properties

• Minerals are classified by six properties: cleavage, color, hardness, luster, streak, and texture

  • Cleavage: when a mineral sample is broken with a hammer, it breaks along planes of weakness that are part of its crystalline structure. These breaks are cleavages

  • Color: color alone cannot be used to identify a mineral as chemical impurities can change its color

  • Hardness: determined by the ability of one mineral to scratch another

    • Mohs scale rates hardness from 1 to 10

  • Luster: the way that the surface reflects light

    • Two types: metallic and nonmetallic

      • Non-metallic is described as glassy, pearly, waxy, and earthy/dull

  • Streak: powder left behind from being rubbed on a hard, rough, white surface

  • Texture

Crust: Rocks

• Rocks are a mixture of minerals that are categorized into three main categories: igneous, sedimentary, and metamorphic

• Igneous Rocks:

  • Created either when magma cools slowly inside the earth’s core or after a volcanic eruption

  • Most common igneous rock is granite

• Sedimentary Rocks:

  • Formed from other rocks or shells breaking down and layering into one

  • If formed close to the shore, these rocks typically have a lot of sand in them versus having more clay in them if formed farther from the shore

• Metamorphic Rocks:

  • All metamorphic rocks start out as either igneous or sedimentary but are transformed by extreme heat and pressure

  • Least common type of rock

Solid Earth Processes: Weathering, Erosion, and Deposition

• Weathering- breaking up of rocks due to chemical or mechanical changes

• Erosion- movement of rock particles by the action of wind, rain, gravity, and other forces of nature

• Deposition- created because of erosion but is the opposite. Rocks are deposited and settle creating new land forms