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Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
Op ch05 lecture_earth3, minerals
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Op ch05 lecture_earth3, minerals

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A mineral is a naturally occurring substance that is solid and stable at room temperature, representable by a chemical formula, usually abiogenic, and has an ordered atomic structure. It is different …

A mineral is a naturally occurring substance that is solid and stable at room temperature, representable by a chemical formula, usually abiogenic, and has an ordered atomic structure. It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition. The exact definition of a mineral is under debate, especially with respect to the requirement a valid species be abiogenic, and to a lesser extent with regards to it having an ordered atomic structure.

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  1. Chapter 5 Patterns in Nature: Minerals LECTURE OUTLINE earth Portrait of a Planet Third Edition ©2008 W. W. Norton & Company, Inc. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  2. Patterns in Nature: Minerals Prepared by Ronald Parker Earlham College Department of Geosciences Richmond, Indiana
  3. Minerals The “building blocks” of rocks, and hence, of Earth.  More than 4,000 are known.  Dozens of new minerals are discovered annually.  Human interest in minerals spans millenia.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  4. Minerals  Developed societies depend on mineral resources. Metals – Iron, copper, lead, zinc, nickel, aluminum, etc.  Non-metals – Gypsum, limestone, aggregate, clay.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  5. Minerals Economically important – Drive world economies.  Historically important – Dictated human history.  Iron.  Copper.  Gold.  Diamonds.  Gems.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  6. Mineral Definition  Geologic definition of a mineral is specialized: Naturally occurring.  Solid.  Formed geologically.  Definite chemical composition.  Ordered atomic arrangement.  Mostly inorganic.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Gypsum Chapter 5: Patterns in Nature: Minerals
  7. Rocks Rocks are Earth materials made from minerals.  Most rocks have more than one kind of mineral.   Example: Granite Potassium feldspar. Quartz. Hornblende.  Some are monomineralic. Limestone (Calcite).  Rock salt (Halite).  Glacial ice.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  8. Crystalline Structure Atoms in a mineral are specifically ordered.  A solid with disordered atoms is called a glass.   Crystalline structure based on atomic patterns. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  9. Crystals Rare minerals displaying flat external faces.  Crystal faces form best in open cavities.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  10. Crystals  Constancy of interfacial angles. The same mineral has the same crystal faces.  Adjacent faces occur at a diagnostic angle.   Faces and angles reflect the atomic arrangement. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  11. Crystal Lattice Ordered atoms in crystals form a 3-D lattice.  Lattices are patterns that repeat in 3 dimensions.  This internal pattern controls mineral properties.  Crystal shape.  Symmetry.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  12. Atomic Bonding Lattice atoms are held in place by atomic bonds.  Bond characteristics govern mineral properties.  5 recognized types of bonds.  Covalent.  Ionic.  Metallic.  Van der Waals.  Hydrogen.   Models depict atoms, bonds, and lattices. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  13. Polymorphs Same composition but different crystal structure.  Polymorphs reveal the importance of bond type.  Diamond and graphite are carbon polymorphs (C).  Diamond – Strong covalent bonds; hardest mineral.  Graphite – Weak Van der Waals bonds; softest mineral.  Diamond Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Graphite Chapter 5: Patterns in Nature: Minerals
  14. Crystal Growth Crystals grow as atoms attach to mineral surfaces.  Growth starts from a central seed crystal.  Growth expands outward as atoms accumulate.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  15. Crystal Growth Outward crystal growth fills available space.  Resulting crystal shape governed by surroundings.  Open space – Good crystal faces grow.  Confined space – No crystal faces.   Crystals grow by… Solidification from a melt.  Precipitation from solution.  Solid-state diffusion.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  16. Atomic Packing  Ionic size (radius) and charge control packing. Ion – Atom charged due to gain or loss of an electron.  Cation – Positive ion due to loss of electron(s).  Anion – Negative ion due to gain of electron(s).   Ionic radii due to # of electrons; anions are bigger. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  17. Atomic Packing Anions and cations bond to neutralize charges.  Anion – Cation “fit” governed by relative size.  Large central cation – Larger number of anions.  Small central cation – Smaller number of anions.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  18. Mineral Physical Properties Characteristics determined by your 5 senses.  Used to ID minerals.  Properties depend upon…  Chemical composition.  Crystal structure.   Some are diagnostic. Pyrite Example: Pyrite (FeS2) Cubic crystals, high specific gravity, striated crystal faces, black streak, metallic luster, dull brassy color, sulfur smell when crushed, erroneously mistaken for gold (fool’s gold).  Minerals have a unique set of physical properties. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  19. Physical Properties  Common properties: Color.  Streak.  Luster.  Hardness.  Specific gravity.  Crystal habit.  Crystal form.  Fracture.  Cleavage.  Needle-like crystal habit Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  20. Color  Color is diagnostic for some minerals. Olivine is olive green.  Azurite is always blue.   Some minerals may exhibit a broad color range.   Quartz (Clear, white, yellow, pink, purple, gray, etc). Color varieties often reflect trace impurities. Quartz – Many colors Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Malachite – Always green Chapter 5: Patterns in Nature: Minerals
  21. Streak Color of a mineral crushed on unglazed porcelain.  Streak is often a useful diagnostic property.   Congruent streak – Streak color same as mineral. Magnetite – Black mineral; black streak.  Incongruent streak – Streak color different than mineral. Chromite – Black mineral; greenish-brown streak. Hematite – Red-brown streak Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  22. Luster The way a mineral scatters light.  Two subdivisions.  Metallic – Looks like a metal.  Nonmetallic.  Vitreous (glassy). Satiny. Silky. Resinous. Pearly. Earthy (dull). Adamantine (brilliant). Quartz – Vitreous luster Satin spar Gypsum – Satiny luster Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  23. Hardness   Scratching resistance of a mineral. Hardness compared to the Mohs Hardness Scale. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Talc, Graphite Gypsum Fingernail 2.5 Calcite Copper Penny 3.5 Fluorite Apatite Glass - Steel 5.5 Orthoclase Steel File 6.5 Quartz Topaz Corundum Diamond Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  24. Crystal Habit Crystal habit is the ideal shape of crystal faces.  Ideal growth requires ideal conditions.  Many terms are used to describe habit.  Cubes Dodecahedra Octahedra Compound Forms Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Blades Rhombohedra Hexagonal Prisms Tetragonal Prisms Chapter 5: Patterns in Nature: Minerals
  25. Crystal Form  Minerals vary in crystal face development. Euhedral – Good crystal faces; grown in open cavity.  Anhedral – No crystal faces; grown in tight space.  Subhedral – Between the two.  Face development indicates growth history.  Anhedral crystals common; euhedral less so.  Amethyst Geode Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  26. Fracture Some minerals lack planes of weakness.  Due to equal molecular bonds in all directions.  These minerals don’t have cleavage; they fracture.   Example: Quartz displays conchoidal fracture. Shaped like the inside of a clam shell. Breaks along smooth curved surfaces. Produces extremely sharp edges. Obsidian Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  27. Cleavage Tendency to break along planes of weakness.  Cleavage produces flat, shiny surfaces.  Described by number of planes and their angles.  Sometimes mistaken for crystal habit.  Cleavage is through-going; often forms parallel “steps.”  Crystal habit is only on external surfaces.   1, 2, 3, 4, and 6 cleavages possible. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  28. Cleavage  Examples of Cleavage:  1 direction  2 directions at 90º Muscovite Mica  2 directions NOT at 90º Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Potassium Feldspar Amphibole Chapter 5: Patterns in Nature: Minerals
  29. Cleavage  Examples of Cleavage:  3 directions at 90º  Halite 3 directions NOT at 90º Calcite Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  30. Mineral Compositions Only about 50 minerals are abundant.  98.5% of crustal mineral mass is from 8 elements.  Oxygen  Silicon  Aluminum  Iron  Calcium  Sodium  Potassium  Magnesium  All others  O Si Al Fe Ca Na K Mg Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak 46.6% 27.7% 8.1% 5.0% 3.6% 2.8% 2.6% 2.1% 1.5% 74.3% of crustal minerals !!! Chapter 5: Patterns in Nature: Minerals
  31. Mineral Classes  Minerals are classified by their dominant anion. Silicates SiO24- Rock-forming mins  Oxides  Sulfides  Sulfates O2SSO42- Magnetite, Hematite Pyrite, Galena Gypsum Halides  Carbonates Cl- or FCO32- Fluorite, Halite Calcite, Dolomite    Native Elements Cu, Au, Malachite (Carbonate) Fluorite (Halide) Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak C Copper, Graphite Native Copper Chapter 5: Patterns in Nature: Minerals
  32. Silicate Minerals Silicates are know as the rock-forming minerals.  They dominate the Earth’s crust.   Oxygen and silicon… Make up 94.7 % of crustal volume, and... 74.3 % of crustal mass. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  33. Silicate Minerals  The anionic unit is the silica tetrahedron. 4 oxygen atoms are bonded to 1 silicon atom (SiO44-).  Silicon is tiny; oxygen is huge.  The silica tetrahedron has a net -4 ionic charge.  The silicate unit can be depicted by…  Spheres. A ball and stick model. Polyhedra. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  34. Silicate Minerals Silica tetrahedra link together by sharing oxygens.  More shared oxygen = lower Si:O ratio; governs…  Melting temperature.  Mineral structure and cations present.  Susceptibility to chemical weathering.  Type of Silicate Structure Formula Si:O Ratio Independent Tetrahedra SiO4 0.25 Double Tetrahedra Si2O7 0.29 Ring Silicates Si6O18 0.33 Single Chains SiO3 0.33 Double Chains Si4O11 0.36 Sheet Silicates Si2O5 0.40 Framework Silicates SiO2 0.50 Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  35. Independent Tetrahedra  Tetrahedra share no oxygens - linked by cations.  Olivine Group. High temperature Fe-Mg silicate. Small green crystals; no cleavage.  Garnet Group. Equant crystals with no cleavage. Dodecahedral (12 sided) crystals. Garnet Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Kyanite Chapter 5: Patterns in Nature: Minerals
  36. Single-Chain Silicates  Single-chain structures bonded with Fe and Mg.  Pyroxene Group. Black to green color. Two distinctive cleavages at nearly 90°. Stubby crystals. Augite is the most common pyroxene. Pyroxene Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  37. Double-Chain Silicates Double chain of silica tetrahedra bonded together.  Contain a variety of cations.   Amphibole Group - Two perfect cleavages; elongate crystals. Hornblende Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  38. Sheet Silicates 2-dimensional sheets of linked tetrahedra.  Characterized by one direction of perfect cleavage.  Mica Group – Biotite (dark) and Mucsovite (light).  Clay Mineral Group – Feldspar weathering residue; tiny.  Muscovite Mica Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  39. Framework Silicates  All 4 oxygens in the silica tetrahedra are shared. Feldspar Group – Plagioclase and potassium feldspar.  Silica (Quartz) Group – Contains only Si and O.  Potassium Feldspar Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  40. Diamonds  Diamonds originate under extremely high pressure. ~ 150 km deep – in the upper mantle.  Pure carbon is compressed into the diamond structure.  Rifting causes deep mantle rock to move upward.  Diamonds are found in kimberlite pipes.  Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals
  41. This concludes the Chapter 5 Patterns in Nature: Minerals LECTURE OUTLINE earth Portrait of a Planet Third Edition ©2008 W. W. Norton & Company, Inc. Earth: Portrait of a Planet, 3rd edition, by Stephen Marshak Chapter 5: Patterns in Nature: Minerals

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