Mineralogy: First Half of Course.docx

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Department
Earth Sciences
Course
GEOL-2126EL
Professor
M Schindler
Semester
Fall

Description
Mineralogy Exam Review Lecture 1 Mineral -Naturally occurring solid with highly ordered atomic arrangement and a definite chemical formula. Usually formed by inorganic processes. -Highly ordered atomic arrangement=long range 3d internal order of atoms -Crystalline Solids Crystals -Bounded by smooth plane surfaces, assume regular geometric forms. Crystal Form -Outward appearace Crystal Morphology -Internal structure Form -Specific combination of crystal faces. Crystal Habit -General shape of crystal (distorted, elongated, stocky) Euhedral = well developed Subhedral = partially developed Anhedral = not developed Luster -Metallic, Vitreous, Resinous, Pearly, Greasy, Silky, Adamantine Flourescence -emmision of light during exposure from UV or X-rays Phosphorescence –emission of light AFTER exposure Cleavage -Tendancy of minerals to break parallel to atomic planes Parting -Breaking along planes of weakness produced by pression, or twinning. Fracture -The way minerals break when there is no cleavage or parting -Conchoidal, Fibrous, Hackly, Uneven Hardness -Resistance of a mineral’s surface to scratching Tenacity -Resistance of mineral to breaking, crushing, bending, tearing Brittle, Ductile, Flexible, Malleable, Elastic Specific Gravity -ratio between weight of material vs weight of water Paramagnetic -Attracted to magnetic field Dimagnetic - Not attracted to magnet Mineralogy Exam Review Lecture 2 S (2) P (6) D (10) F (14) orbitals Electronegativity -ability of an atom to attract electrons Chemical Bonds Ionic -Electrical. Strong. High Symmetry. Covalent -Sharing Electrons, single, double, triple bonds. Metallic -Free electons. Good conductivity, ductile. Van der Waals -Weakest (graphite). Polar Hydrogen -Stronger than above, but polar Paulings Rules -Rc/Ra = coordination #. Cation-anion distance = sum of radii -Strength of bond = valence/CN# (eg [6]Na(1+) = +1/6) -Structure will be stable if sum of bonds = charge of anion -Sharing of edges/faces means weak structure Crystallography Crystallography =Study of crystalline solids & the principles that govern their growth, external shape, and internal structure. Morphology =Internal arrangement of atoms and the internal symmetry. Motif -Fundamental part of a symmetric design that, when repeated, creates the whole pattern. 10 possible 2D point Groups 32 possible 3D point Groups Translations (Lattices) -A symmetric translation at the atomic level involving repeated distances. Space Groups = atom symmetry Point Groups = Crystal symmetry Crystal Faces = limiting surfaces of growth {111} = crystal form (111) = face direction [111] = face Form = Set of symmetrically equivalent faces Mineralogy Exam Review Stereographic -Solid lines = perpendicular mirrors -Diamond with 2-fold in center = 4-fold roto Octahedron {111} Cube {001} Dodecadron {011} Ore Deposits LMI Layered Mafic Intrusions S. Africa, Antartica Komatites Lava Chamber Africa, NWT SIC impact structure Sudbury Pegmatites coarse-grained granites High concentrations of rare elements Late-stage water rich fluids Hydrothermal Movement of hot gas & fluids causing dissolution of metals and precipitation somewhere else Cu, Pb, Zn, Au, Ag, U, As, Sb, Hg all formed this way. MVT Mississippi Valley Type Sedimentary Deposit, Sphalerite forming VMS Volcanogenic Massive Sulfides Form at or near sea-floor from ejection of hot metal-rich hydrothermal fluids. BIF Banded Iron Formation. Magnetite & Hematite alternating. Due to oxygenation of early ocean. Supergene High Sulfur at bottom, high metals at top Due to oxidation Evaporites Carbonates>Sulfates>Chlorides Mineralogy Exam Review Native Elements CCP structure = ABCABC HCP structure = ABABAB  GOLD (Au) Cubic CCP H=2.5-3 D=18 Very Ductile & Malleable Yellow, metallic Luster, opaque Silver has same atomic size, so up to 20% of mass is interchangeable Placer Deposits (Klondike) Primary Hydrothermal (Ontario, California) Apps: Jewellrey, dentistry, electronics  Silver (Ag) Cubic CCP H=2.5-3 D=10-12 Ductile, Silver, Metallic, opaque Apps: photography, jewellrey, electronics, tableware Hydrothermal, no placer  Copper (Cu) CCP Harder than gold or silver, D=8-9 Copper colour, (weathered = green/black) Ductile, opaque Forms elementally or dentritic Two famous alloys (bronze- Cu+Sn) (Brass- Cu +Zn) Apps: electronics, currency Summary of gold group Isostructurally CCP, point group 4/m, 3bar, 2/m Soft, mallesable, metallic, hackly, low melting, high D  Platinum (Pt) CCP H=4-4.5, D=21 Grey like steel, but heavier Forms in LMI and SIC (esp S. Africa) Apps: Jewelry, Inverstments, industrial, automotive Mineralogy Exam Review  Iron (Fe) Kamacite & Taenite (both form in meteroites) Taenite > Ni than Kamacite D< than Pt  Sulfur (S) Orthorhombic, forms pyramids. 2/m 2/m 2/m H=1.5-2.5, D=2 S-8 rings in Sufur. Orthomrombic =P, Monoclinic = T Apps: Fertilizer, Acid, Rubber production  Diamond (C) Cubic Isometric 4/m, 3bar, 2/m {111} SP^3 hybrid. 4 carbons around each carbon, covalent H=10, cleavage = [111], adamantine Strong dispersion of light, called Fire High P mineral. Forms in placer deposits, Mina Gerais, Namibia Also Komatites Apps: drilling,
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