Definition of Minerals PDF

Definition of Minerals Overview: A mineral is a naturally occurring, homogeneous solid with a definite chemical composition and an ordered atomic structure. It forms through geological processes and possesses specific physical properties that distinguish it from other substances. Natural Occu...

Definition of Minerals Overview: A mineral is a naturally occurring, homogeneous solid with a definite chemical composition and an ordered atomic structure. It forms through geological processes and possesses specific physical properties that distinguish it from other substances. Natural Occurrence: ○ Formed through natural geological processes. ○ Not created artificially or in laboratories. Inorganic Composition: ○ Must not contain organic materials. ○ Produced by natural means without biological involvement. Homogeneous Solid: ○ Uniform appearance and consistency throughout. ○ Chemical composition must be uniform as well. Ordered Structure: ○ Exhibits a crystalline structure (crystal lattice). ○ Crystals are arranged in a regular, repeating three-dimensional pattern. ○ Distinction between crystalline solids (ordered) and amorphous solids (disordered aggregates). Definite Chemical Composition: ○ Each mineral has a specific chemical formula that defines its composition. ○ Variations in composition can lead to different minerals. Mineral Classification Overview: Mineral classification involves categorizing minerals based on their chemical composition and structure. Key categories include polymorphs, which share a common chemical formula but differ in crystal structure, and mineraloids, which do not have a crystalline structure. Polymorphs: ○ Minerals with the same chemical composition but different crystal structures. ○ Example: Diamond and graphite are both forms of carbon (C) but exhibit different physical properties due to their distinct arrangements of atoms. ○ Importance of uniformity in appearance and solid state. Mineraloids: ○ Substances that resemble minerals but lack a definite crystalline structure. ○ Examples include opal and obsidian, which do not form regular crystal lattices Key Characteristics of Minerals: ○ Homogeneous, naturally occurring substances formed through geological processes. ○ Definite chemical composition and highly ordered atomic structure. ○ Specific physical properties such as hardness, luster, and cleavage. Crystalline Structure: ○ Refers to the arrangement of atoms within a mineral. ○ Crystalline solids form a regular repeating three-dimensional lattice. ○ Amorphous solids lack a specific order or arrangement in their atomic structure. Physical Properties of Minerals Overview: The physical properties of minerals are essential for their identification and classification. These properties include characteristics such as color, hardness, and cleavage, which help distinguish one mineral from another based on their unique features. Color: ○ Used for easy identification of minerals. ○ Result of how minerals absorb light. Streak: ○ Color of the powder produced when a mineral is scratched against a surface.  ○ Provides more consistent color information than the mineral itself. Hardness: ○ Resistance of a mineral to scratching. ○ Measured using the Mohs scale, ranging from talc (1) to diamond (10). Cleavage: ○ Describes how minerals break along specific planes of weakness in their crystalline structure. ○ Results in smooth, flat surfaces. Fracture: ○ Occurs when minerals break in irregular patterns without cleavage. ○ Can result in jagged or uneven surfaces. Crystalline Structure: ○ Arrangement of atoms within a mineral. ○ Determines the shape and symmetry of the mineral's crystals. Transparency: ○ Ability of a mineral to transmit light. ○ Ranges from transparent to opaque. Magnetism: ○ Some minerals exhibit magnetic properties. ○ Useful for identifying certain minerals like magnetite. Tenacity: ○ Resistance of minerals to stress (crushing, bending, breaking). ○ Classifies minerals as brittle, malleable, elastic, etc. Luster: ○ Appearance of a mineral's surface in reflected light. ○ Categories include metallic, glassy, pearly, and dull. Odor: ○ Distinct smell released during chemical reactions with water, heat, air, or friction. Specific Gravity: ○ Measure of density comparing the weight of a mineral to that of water. ○ Indicates how heavy a mineral feels relative to its size. Chemical Properties of Minerals Silicate- largest and most abundant mineral contains silicon & oxygen. Carbonate - mostly found in marine environments. Sulfate - forms in high evaporation rates. Halide - Natural Salts Sulfide- coppers, lead, metals Phosphate- mineral and phosphorus Native Elements - contains intermetallic elements/compound ROCKS - Formation of minerals ROCK CYCLE: IGNEOUS ROCK —--------- SEDIMENTARY ROCK —----------METAMORPHIC ROCK A. IGNEOUS ROCKS - The melting, cooling, and crystallization; the result of volcanic activity FORMATION OF IGNEOUS ROCKS: 1. INTRUSIVE IGNEOUS ROCK - Also known as PLUTONIC ROCK - Formed when magma hardens beneath the earth’s surface. 2. EXTRUSIVE IGNEOUS ROCK - Lava hardens outside or happens outside - Also known as VOLCANIC ROCK B. SEDIMENTARY ROCK - Formed by weathering, erosion, deposition, compaction, and cementation.  1. CHEMICAL SEDIMENTARY ROCK - Forms when minerals that were dissolved in water and as water evaporates, minerals are left behind. 2. CLASTIC SEDIMENTARY ROCK - Formed by rock fragments that are carried away from their source by water, wind, and ice, and are compressed and glued together. 3. BIOCHEMICAL SEDIMENTARY ROCK - From living organisms - APHANITIC: small crystals that are not visible in the naked eye. C.METAMORPHIC ROCK - Metamorphism/ Protolith: process in which heat, pressure, mechanical stresses, and chemical processes change existing rock. CLASSIFICATIONS: - FOLIATED: breaks along easily and flat - NON- FOLIATED: has no “linear” quality to the rocks Earth Processes Overview: Earth processes encompass the dynamic geologic activities that continuously shape the planet's surface. These processes, driven by internal heat and external forces, include tectonic movements, erosion, sediment deposition, and the influence of Earth's magnetic field, contributing to the ongoing evolution of the Earth. Geologic Processes: ○ Continuous shaping of Earth's surface since its formation. ○ Involves both endogenic (internal) and exogenic (external) processes. Surface Evolution: ○ Changes in landforms due to various geological activities. ○ Influenced by weathering, erosion, and sedimentation. Earth's Magnetic Field: ○ Generated by the movement of molten iron in the Earth's outer core. ○ Plays a crucial role in protecting the planet from solar radiation. Plate Tectonics: ○ Movement of Earth's lithospheric plates due to mantle convection. ○ Causes earthquakes, volcanic activity, and mountain building. Mountain Formation: ○ Result of tectonic processes such as folding and faulting. ○ Includes features like anticlines, synclines, rift valleys, and escarpments. River Erosion: ○ Rivers erode landscapes, creating valleys and floodplains. ○ Transport sediments downstream, reshaping the terrain. Sediment Deposition:  ○ Accumulation of sediments in riverbeds, deltas, and ocean basins. ○ Contributes to the formation of new landforms and habitats. Endogenic Processes: ○ Geologic processes occurring beneath Earth's surface. ○ Powered by the internal heat of the Earth, leading to large-scale landform changes. > Tectonic Processes:Cause land movement and seismic activity (diastrophism). Folding: Creation of mountains through compression. Faulting: Formation of rift valleys and other structures. Lateral Faulting: Strike-slip faults causing horizontal displacement. > Igneous Processes: the formation and crystallization of magma or lava. Volcanism: Volcanic eruptions forming volcanoes. Plutonism: Intrusions of igneous rock into existing formations. ENDOGENIC PROCESS Overview: Endogenic processes are geological activities that occur beneath the Earth's surface, driven by its internal heat. These processes play a crucial role in landform building and transformation, continuously shaping the planet's structure over time. Geologic Processes: ○ Continuous shaping of the Earth's surface. ○ Operate since the early stages of planetary evolution. ○ Involve movements and shifts within the Earth’s interior. Internal Heat: ○ Powered by the Earth's core, primarily through convection currents in the mantle. ○ Drives various geological phenomena including plate tectonics and volcanic activity. 1 Landform Building: ○ Formation of mountains through uplift of rocks. ○ Creation of rift valleys and other features due to tectonic movements. ○ Rivers and sediment deposition shape floodplains and ocean basins. A. Igneous Processes Overview: Igneous processes involve the formation and crystallization of magma or lava, leading to volcanic activity (volcanism) and the creation of igneous intrusions (plutonism). These processes are fundamental in shaping the Earth's surface and understanding geological phenomena. Magma Formation: ○ Occurs through melting of rocks in the mantle or crust due to temperature and pressure changes. ○ Factors influencing magma formation include heat, pressure, and the presence of water. Lava Crystallization: ○ The process where molten lava cools and solidifies into igneous rock. ○ Can occur rapidly during eruptions or slowly beneath the surface. Volcanism Overview: Volcanism refers to the geological processes that result in the expulsion of lava, gases, and other materials from the Earth's interior through volcanic eruptions. It encompasses various phenomena related to volcanoes, including their formation, eruption styles, and underlying sources of heat. Volcanic Eruptions: ○ Involves the release of magma, gas, and ash from a volcano.  ○ Different eruption styles include: Vulcanian: Sustained explosions occurring in series. Plinian: most intense/strongest type of eruption characterized by powerful explosive activity. Hawaiian: sparks Surtseyan: Has water Strombolian: its lava is viscous like fireworks Volcano Types: ○ Various classifications based on shape, eruption style, and composition. ○ Common types include shield volcanoes, stratovolcanoes, and cinder cone volcanoes. ❖ Shield: large and broad vent with shallow slope ❖ Cinder: Steep Volcano ❖ Composite: common volcano; not too steep, not too wide Volcanology: ○ The scientific study of volcanoes, lava, magma, and associated geological, geophysical, and geochemical phenomena. ○ Focuses on understanding eruption mechanisms, predicting volcanic activity, and assessing hazards. Sources of Volcanism: ○ Radioactive Decay: Heat generated from the decay of radioactive elements within the Earth. ○ Original Heat: Residual heat from the planet's formation. ○ Friction: Heat produced from tectonic plate movements and interactions. Plutonism: ○ Refers to the formation of igneous intrusions when magma cools and solidifies underground. ○ Results in the creation of plutons, which can form large bodies of granite or other igneous rocks B. Tectonic Processes: Movement of land resulting in earthquakes (Diastrophism). Folding: Formation of anticlines and synclines, contributing to mountain ranges. Faulting: Development of rift valleys, grabens, and escarpments. Lateral Faulting: Includes strike-slip faults, indicative of tectonic activity. RICHTER SCALE - magnitude of the earthquake MERCALLI SCALE = intensity of the earthquake. Exogenic Processes Overview: Exogenic processes are geological phenomena that occur at or near the Earth's surface, leading to the wearing away of the surface. These processes are influenced by external factors such as the atmosphere, hydrosphere, and biosphere, and are primarily powered by solar energy. Definition: ○ Processes occurring at or near the Earth's surface. ○ Responsible for surface wear and changes. ○ Related to external environmental factors. Geological Phenomena: ○ Include weathering, erosion, mass movement (mass wasting), and sedimentation. ○ Involve interactions with water, soil cover, and geological features. Surface Changes: ○ Result from various exogenic processes like: Weathering: Breakdown of rocks and minerals. Erosion: Wearing away of the Earth's surface by wind, water, or ice. Mass Movement: Movement of soil and rock down slopes due to gravity. Sedimentation: Accumulation of sediments in new locations. Energy Source: ○ Primarily driven by solar energy. NOTE: Influences weather patterns, water cycles, and biological activity that contribute to exogenic processes Exogenic Processes Types Overview: Exogenic processes are geological phenomena that occur at or near the Earth's surface, leading to the wearing away and alteration of landforms. These processes include weathering, erosion, mass movement, and sedimentation, primarily driven by solar energy and influenced by atmospheric, hydrospheric, and biospheric factors. 1. Weathering: ○ Disintegration and decomposition of rocks in situ (no transportation). ○ Produces regolith through mechanical or chemical processes. ○ Begins in microscopic spaces, cracks, and other rock cavities. ○ Types of Weathering: Physical (Mechanical) Weathering Chemical Weathering Biological Weathering Physical(Mechanical) Weathering Overview: Physical weathering is the mechanical breakdown of rocks without altering their chemical composition. It occurs through various forces such as temperature changes, pressure variations, and other environmental factors, leading to the disintegration of rock into smaller fragments. Mechanical Forces: ○ Involves physical processes that exert stress on rocks. ○ Common mechanisms include frost wedging, salt wedging, and exfoliation. Temperature Changes: ○ Thermal expansion and contraction cause rocks to crack. ○ Extreme heat or cold can lead to significant structural changes in rocks. Pressure Changes: ○ Uplift of buried rocks releases pressure, causing fractures. ○ Exfoliation occurs when outer layers peel away due to reduced pressure. Examples: ○ Frost Wedging: Water enters cracks, freezes, expands, and breaks the rock apart. ○ Salt Wedging: Salt crystals form from evaporating water, expanding and fracturing rocks. ○ Exfoliation Domes: Formed by thermal expansion/contraction (e.g., Stone Mountain, GA). ○ Soil Cracks: Occur during extreme heat or drought conditions, illustrating physical weathering effects. Chemical Weathering Overview: Chemical weathering is the process by which rocks undergo chemical reactions that lead to their breakdown and transformation into new or secondary minerals. This process alters the original properties of the minerals in the rock, often resulting in significant changes to the landscape. Chemical Reactions: ○ Involves various chemical processes that break down minerals within rocks. ○ Key agents include oxidation, hydrolysis, and acid rain. Secondary Minerals: ○ New minerals develop as a result of chemical weathering. ○ These minerals can replace the original minerals, altering the rock's composition and properties. Oxidation: ○ A reaction where substances combine with oxygen. ○ Commonly affects iron-bearing minerals, leading to rust formation and weakening of the rock structure.  Hydrolysis: ○ The chemical breakdown of minerals when they react with water. ○ Important for the alteration of feldspar into clay minerals. Acid Rain: ○ Precipitation that contains acidic components, primarily from atmospheric pollution. ○ Causes metals and stones to corrode or deteriorate, changing their physical and chemical properties. BIOLOGICAL WEATHERING - Plants and animals contributes 2. Erosion: ○ Process of wearing away the Earth's surface by wind, water, or ice. ○ Moves rock debris from one location to another. ○ Occurs during rainfall, surface runoff, flowing rivers, and human activities like mining. 3. Sedimentation: ○ Geological process where sediments, soil, and rocks are added to a landform. ○ Involves transport of previously weathered materials by wind, ice, water, and gravity. ○ Deposition occurs when kinetic energy decreases, resulting in layer buildup. 4. MASS WASTING - Movement of large masses and materials down due to gravity. Can be triggered by factors such as saturation, earthquakes, or human activity. TYPES: 1. MudFlow - Water and Soil Mixing 2. Debris or Rockflow - large amounts of sediments fall down the slope. 3. Slump - slow movement of soil along a surface 4. Creep- Slow mass wasting process that takes months/years.