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Chapter 1. Minerals

Chapter 1. Minerals. Formation of Minerals. Minerals form when atoms of elements combine through chemical bonding Formation of Sodium Chloride Sodium : soft, silvery metal; Chorine : green, poisonous gas

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Chapter 1. Minerals

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  1. Chapter 1. Minerals

  2. Formation of Minerals • Minerals form when atoms of elements combine through chemical bonding • Formation of Sodium Chloride • Sodium: soft, silvery metal; Chorine: green, poisonous gas • Sodium atom loses one electron and chlorine atom gains one electron while forming sodium chloride

  3. Periodic Table

  4. Formation of Minerals cont’d.. • Atom • Atomic Number • Ions • Ionic bonding • Covalent bonding • Atomic mass or Mass Number • Isotopes • Radioactive Decay

  5. Formation of Minerals cont’d.. • Atom • Atom is characterized by a relatively small nucleus of tightly packed protons and neutrons with a surrounding cloud of electrons • Atomic Number • Number of Protons (or number of electrons) • Ions • Electrically charged atoms • Ionic bonding • electron transfer • Covalent bonding • electron sharing • Atomic mass or Mass Number • Number of Protons + Number of Neutrons

  6. Formation of Minerals cont’d.. • Isotopes: • Atoms of the same element with similar number of protons but different number of neutrons • Radioactive Decay • The process of disintegration of isotopes with unstable nuclei • Occurs when the forces that bind the nucleus are not strong enough to keep it together • Associated with the radiation of energy and particles

  7. Characteristics of Minerals • Natural Inorganic (never alive) Solids

  8. Characteristics of Minerals cont’d.. • Internal Structure

  9. Characteristics of Minerals cont’d.. • Composition of minerals • Minerals have definite chemical composition, in which specific elements occur in definite proportions

  10. The Growth of Minerals • Crystal Growth • Accomplished by crystallization during which atoms are added to a crystal face • Environment suitable for crystal growth • Proper concentration of the kinds of atoms or ions required for a particular mineral • Proper temperature and pressure

  11. Physical Properties Properties used to identify minerals • Streak • Cleavage • Fracture • Hardness • Luster • Specific gravity • Other properties

  12. Physical Properties • Properties used to identify minerals • Streak • Color of the mineral in its powder form • Cleavage • The tendency of a mineral to break along planes of weak bonding • Types of cleavage: basal or sheet (1 direction); prismatic (2 directions); cubic (3 directions at right angles); rhombohedral (3 directions not at right angles); octahedral (4 directions); dodecahedral (6 directions)

  13. Properties used to identify minerals • Fracture • Describes the Breakage of mineral, not along cleavage planes • Hardness • Measure of mineral’s resistance to abrasion • Moh’s Hardness Scale: 1-10

  14. 6. K-feldspar Samples of Minerals on Moh’s Hardness Scale 2. Gypsum 1. Talc 7. Quartz 3. Calcite 8. Topaz 4. Fluorite 5. Apatite 10. Diamond 9. Corundum

  15. Physical Properties cont’d.. • Luster • Quality and intensity of light that is reflected from the surface of a mineral Few Examples of Luster • Vitreous - the most common luster, it simply means the look of glass • Metallic - the look of metals • Adamantine - very gemmy crystals • Pearly - the look of a pearl • Resinous - the look of resins such as dried glue or chewing gum • Silky - the look of silk, similar to fibrous but more compact

  16. Physical Properties cont’d.. • Specific gravity • Measure of heaviness of a mineral • Low, medium, high • Special properties • Magnetism, reaction to acid, taste, feel (soapy or greasy)

  17. Abundance of elements in the Continental Crust

  18. Rock-forming Minerals • Most abundant few dozen minerals

  19. Types of Rock-forming Minerals • Silicates • A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons • Non-silicates • Minerals other than silicate minerals • carbonates, oxides, sulfides, sulfates, halides, native elements

  20. Silicate Minerals • Most of earth’s crust (more than 95 %) and mantle are made of silicate minerals • A group of minerals containing atoms of silicon and oxygen linked in tetrahedral units called silica tetrahedrons • Silica Tetrahedron = 1 Silicon & 4 Oxygen atoms

  21. Silicate Minerals • Common elements such as Fe, Mg, Na, Ca, K and Al combine with Si and O2 to make silicate minerals • Characterized by different types of silicate structures

  22. Silicate Minerals cont’d… • Silicate Structures • Defined by the configuration of silicon-oxygen tetrahedrons in the silicate minerals

  23. Non-silicate Minerals • Minerals other than silicate minerals • Most of these are carbonates or sulfates • Typically form at low temperatures and pressures near earth’s surface • Examples • Calcite, Dolomite, Halite, Gypsum, Pyrite, Galena, Magnetite

  24. Non-silicate Minerals cont’d… • Minerals of Economic value • Ores of metals and gemstones • Examples • Galena (lead) • Sphalerite (zinc) • Chalcopyrite (copper) • Hematite (iron) • Diamond (carbon) • Emerald (beryl) • Ruby and sapphire (corundum)

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