Earth Materials: Minerals and Properties

• Earth materials encompass minerals, rocks, soil, water, air, and organic matter.
• These materials support life, land structure, and human civilization.

Minerals

• Minerals are naturally occurring, inorganic solids.
• They possess a crystalline structure and a definite chemical composition.
• Examples of minerals include salt, sulfur, quartz, and graphite.

Physical Properties of Minerals

• Color is an easily observable but unreliable property for mineral identification.
• Streak is the color of a mineral in powdered form and is determined by rubbing it on a streak plate.
• Hardness is measured using the Mohs scale, ranging from 1 (talc) to 10 (diamond).
• Cleavage refers to breaks along smooth planes, while fracture refers to irregular breakage patterns.
• Crystalline Structure refers to the ordered arrangement of atoms in a repeating pattern.
• Transparency (Diaphaneity) describes how light passes through a mineral, categorized as transparent, translucent, or opaque.
• Magnetism is when certain minerals attract or repel magnets.
• Tenacity measures a mineral's resistance to breaking, bending, or deforming.
• Luster describes how light reflects off a mineral's surface, such as metallic, dull, or glassy.
• Odor is when certain minerals emit a distinct smell when rubbed, heated, or exposed to air.
• Specific Gravity is the density of a mineral compared to water.

Types of Rocks

• Rocks are classified into igneous, sedimentary, and metamorphic types.

Igneous Rocks

• Igneous rocks form from the cooling and solidification of magma or lava through crystallization.
• Examples include granite and basalt.

Sedimentary Rocks

• Sedimentary rocks form from the deposition and cementation of sediments (plants, dead animals and other minerals), and lithification.
• Most sedimentary rocks are found in bodies of water like oceans, seas and rivers.
• Examples include sandstone and limestone.

Metamorphic Rocks

• Metamorphic rocks form when igneous or sedimentary rocks undergo high pressure and temperature.
• This results in changes to the structure and mineral composition.
• Examples include gneiss and migmatite.
• Metamorphism involves heat, pressure, and recrystallization.

Rock Cycle

• The rock cycle describes the transformation of rocks from one type to another.
• Igneous rocks undergo weathering and erosion to form sedimentary rocks.
• Sedimentary rocks subjected to heat and pressure become metamorphic rocks.
• Metamorphic rocks melt into magma, which cools to form igneous rocks.

Types of Exogenous Processes

• Exogenous processes occur on the Earth's surface.

Weathering

• Weathering is the disintegration of rocks, soil, and minerals.
• It occurs due to contact with Earth's systems.
• Physical weathering breaks down rocks through mechanical forces like temperature changes.
• Chemical weathering involves chemical reactions that alter minerals, such as oxidation and hydrolysis.

Erosion

• Erosion is the wearing away of the Earth's surface by natural forces (wind, water, ice).
• Rainfall, surface runoff, and human activities like deforestation and mining cause erosion.

Mass Wasting

• Mass wasting is the movement of large masses of materials down slopes due to gravity.
• Debris flow involves rapid movement of sediments down a slope.
• Mudflow is a combination of soil and water flowing down a slope.
• Slump is a slow movement of soil along a curved surface.

Sedimentation

• Sedimentation is the accumulation of materials (soil, rocks) that settle on the ground.

Endogenous Processes

• Endogenous processes occur within the Earth and are driven by thermal energy from the mantle.
• These processes shape the Earth's surface leading to earthquakes and volcanic activity.

Magmatism

• Magmatism is the original material that forms igneous rocks, originating beneath the Earth's surface at extreme heat.
• Magma rises through the mantle and can lead to volcanic eruptions when it escapes through cracks in the Earth's crust.

Volcanism (or Plutonism)

• Volcanism occurs when magma escapes from the mantle and travels to the surface, forming volcanic materials.
• Magma erupts and becomes lava, which solidifies to form new volcanic rock.

Metamorphism

• Metamorphism alters the materials making up rocks due to changes in pressure and temperature.