Minerals and Rocks Overview

Minerals and Rocks

• Minerals are naturally occurring inorganic substances with a definite chemical composition and physical properties.
• Minerals are solid forms in the crust and liquid in the interior.
• The basic source of minerals is hot magma.
• Natural gas is an example of organic minerals.

Physical Characteristics of Minerals

• Crystal Form: Internal arrangement of atoms.
• Cleavage: Tendency to break along specific planes.
• Fracture: Irregular breakage.
• Luster: Appearance in terms of light reflection.
• Color: Determined by molecular structure.
• Transparency: Degree of light passing through.
• Structure: Arrangement of individual crystals.
• Hardness: Resistance to being scratched.
• Specific Gravity: Ratio of the density of a substance to the density of water.

Important Minerals of the Earth's Crust

• Feldspar: Silicon and oxygen are common elements.
• Quartz: Important component of sand and granite primarily silica.
• Pyroxene: Contains calcium, aluminum, magnesium, iron, and silica.
• Olivine: Contains magnesium, iron, and silica.
• Amphibole: Contains aluminum, calcium, silica, iron, and magnesium.
• Mica: Consists of potassium, aluminum, magnesium, iron, and silica.

Types of Rock

• Rocks are aggregates of one or more minerals.
• They are not composed of a definite chemical composition.
• Petrology is the science of rocks.

Igneous Rocks

• Formed from the cooling of lava.
• Two types: intrusive (slow cooling, larger grains) and extrusive (sudden cooling, small grains).
• Hard and do not contain fossils.
• Do not allow water to pass through.

Sedimentary Rocks

• Formed by sedimentation.
• Layered.
• Contain fossils.
• The process of sedimentary rock formation is called lithification.
• Three types: mechanically formed, chemically formed, and organically formed.

Metamorphic Rocks

• Formed due to recrystallization.
• Formed due to pressure and temperature.
• Very smooth.
• Sometimes contain very precious stones.
• Composed of layers.

Rock Cycle

• A cyclical process involving the transformation of rocks from one type to another.
• Magma crystallizes into igneous rock, which can erode and deposit sediments to form sedimentary rock.
• Sedimentary rocks can be transformed into metamorphic rock via heat and pressure.
• Metamorphic rock can be melted and reformed as magma, and the cycle repeats.

Geomorphic Processes

• Endogenic forces (internal) cause physical and chemical actions on Earth's materials.
• Diastrophism and volcanism are examples of endogenic processes.
• Weathering, mass wasting, erosion, and deposition are exogenic processes (external).
• Endogenic energy comes from within the Earth (radioactivity, rotation, tidal friction, primordial heat).
• Diastrophism describes processes that move or elevate parts of the Earth's crust; includes orogenic, epeirogenic processes, earthquakes, and plate tectonics.
• Volcanism involves the movement of molten rock towards the surface and the formation of volcanic features.

Weathering

• Weathering is the action of atmospheric elements on Earth materials.
• Two types: chemical and physical.
• Chemical weathering involves the decomposition or dissolution of rocks.
• Physical weathering involves the breakdown of rocks into smaller pieces.

Mass Movement

• Mass movements transfer rock debris down slopes due to gravity.
• Types: slow (creep, solifluction) and rapid (mudflows, earthflows, debris avalanches, landslides).

Erosion and Deposition

• Erosion involves the removal and transportation of rock debris.
• Deposition involves the laying down of eroded materials.

Landforms

• Landforms are shapes of the Earth's surface.
• Landforms are created by various geomorphic agents (e.g., running water, ice, wind, groundwater, waves).
• Types categorized by the processes that formed them (e.g., running water, ground water, glaciers, waves).