09a-MineralsCV (1)

Module Overview

• Module 3: Geosphere

• Topics Include:

  • Minerals & Mineral Resources

  • Rock Cycle

  • Volcanoes, Resources & Climate

  • Earthquakes, Plate Tectonics & Life

  • Sedimentary Rocks & Carbon Cycle

  • Soils

Definition of a Mineral

• Key Characteristics:

  1. Naturally occurring

  2. Inorganic

  3. Solid

  4. Predictable chemical composition

  5. Regular internal arrangement of atoms (crystal structure/lattice)

• Non-Minerals Examples:

  • Synthetic ruby (not a mineral)

  • Natural ruby (is a mineral)

  • Organic substances (e.g., wood)

  • Water (not a mineral) vs. ice (is a mineral)

Mineral Formation and Destruction

• Mineral Formation:

  • Atoms bond to form minerals, which make up rocks. For example:

    • Sodium (Na) and Chlorine (Cl) form halite (rock salt)

  • Ways Crystals Form:

    1. Crystallization (Solidification): Crystals grow from cooling magma/lava, or when liquid H2O freezes.

    2. Precipitation from a Solution: As sea-water evaporates or around volcanic vents, dissolved ions crystallize.

       • Example: Halite forms from saltwater evaporation and native sulfur from volcanic gas.

• Mineral Destruction:

  • Melting: Heat breaks atomic bonds.

  • Dissolving: Solvents like water break bonds.

  • Chemical Reactions: Reactive materials, such as acids, break bonds.

  • Example of Reaction:

    • Calcite + HCl → H2O + CO2 + Ca2+ + 2 Cl– ions

Mineral Composition

• Diversity of Minerals:

  • Over 2500 recognized minerals; approximately 50 are abundant.

  • 98% of crustal mineral mass is from eight elements:

    • Oxygen (46.6%)

    • Silicon (27.7%)

    • Aluminum (8.1%)

    • Iron (5.0%)

    • Calcium (3.6%)

    • Sodium (2.8%)

    • Potassium (2.6%)

    • Magnesium (2.1%)

  • Remaining elements constitute only 1.5% of Earth’s crust.

Types of Minerals

• Silicate Minerals:

  • Contain Silicon (Si) and Oxygen (O)

  • Make up about 92% of Earth's crust by volume.

  • Include various cations (e.g., Ca, Na, Fe, Mg).

• Rock Forming Minerals:

  • Dark Minerals (e.g., Biotite, Pyroxene)

  • Light Minerals (e.g., Quartz, Potassium Feldspar)

Important Mineral Groups

• Sulfides:

  • Example: Pyrite (FeS2) - fool's gold and ore of iron.

  • Example: Galena (PbS) - lead ore.

• Sulfates:

  • Example: Gypsum (CaSO4·2H2O) - used in drywall and plaster.

• Carbonates:

  • Example: Calcite (CaCO3) - used in concrete and antacids.

• Halides:

  • Example: Halite - table salt.

Physical Properties for Mineral Identification

• Luster: Reflection of light (metallic vs. non-metallic).

• Color: Generally unreliable but can indicate variations.

• Streak: Color of powdered mineral; consistent regardless of mineral color.

• Hardness: Measured on Mohs scale (1=softest, 10=hardest).

• Cleavage: Planes of weakness; minerals can break along these planes.

• Fracture: Random breakage pattern of minerals lacking cleavage.

Other Properties of Minerals

• Specific Gravity: Density compared to water.

• Magnetism: Some minerals can attract magnets.

• Effervescence: Reaction with acid (e.g., calcite with HCl).

• Taste: Salts like halite exhibit a salty taste.

Review Points

• Minerals as the building blocks of rocks.

• Five key parts of a mineral's definition.

• Processes forming and destroying minerals are crucial for understanding environments.

• Important chemical reactions like calcite's effervescence related to the carbon cycle.

• Properties used for mineral identification are essential for classification.

Key Concepts: Minerals and Their Significance

• Minerals as Building Blocks: Minerals are the fundamental components of rocks.

• Five Parts of a Mineral's Definition:

  1. Naturally occurring

  2. Inorganic

  3. Solid

  4. Predictable chemical composition

  5. Regular internal arrangement of atoms (crystal structure/lattice)

• Classifying Materials: Understanding the five key parts of a mineral's definition is essential for classifying materials as minerals or non-minerals.

• Processes that Form Minerals:

  • Atoms bond to form minerals through:

    1. Crystallization (Solidification): Crystals grow from cooling magma/lava or from the freezing of liquid water (H2O).

    2. Precipitation from a Solution: Dissolved ions in seawater or around volcanic vents crystallize as water evaporates.

• Processes that Destroy Minerals:

  1. Melting: Heat disrupts atomic bonds.

  2. Dissolving: Solvents like water break bonds.

  3. Chemical Reactions: Reactive materials (e.g., acids) can disrupt bonds.

• Significance of the Calcite Reaction: The reaction of calcite with hydrochloric acid (HCl) is significant to the carbon cycle. Understanding this reaction illustrates the interactions between minerals and environmental processes:

  • Calcite + HCl → H2O + CO2 + Ca2+ + 2 Cl– ions

• Eight Most Abundant Elements in Earth's Crust:

  1. Oxygen (46.6%)

  2. Silicon (27.7%)

  3. Aluminum (8.1%)

  4. Iron (5.0%)

  5. Calcium (3.6%)

  6. Sodium (2.8%)

  7. Potassium (2.6%)

  8. Magnesium (2.1%)

• Rock Forming Minerals:

  • Elements: Silicon (Si) and Oxygen (O)

  • Significance: Rock forming minerals are crucial for the composition of the Earth's crust, making up about 92% by volume.

• Remaining Elements: It is significant that all other elements constitute only 1.5% of the Earth's crust, as it highlights the dominance of a few elements in forming the vast majority of minerals.

• Defining Mineral Groups: Mineral groups are defined based on common properties or chemical compositions, which is important for understanding their characteristics, behaviors, and how they interact within geological processes.

• Properties Used for Mineral Identification:

  • Luster, Color, Streak, Hardness, Cleavage, Fracture, Specific Gravity, Magnetism, Effervescence, Taste.

Understanding these properties is essential for classifying and identifying minerals accurately in geological contexts.