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Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300

Introduction to Mineralogy Dr. Tark Hamilton Chapter 4: Lecture 16 The Chemical Basis of Minerals (Perovskite & Spinels). Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300. Perovskite CaTiO 3 Structure CCP Orthorhombic 2/m2/m2/m, dipyramidal.

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Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300

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  1. Introduction to MineralogyDr. Tark HamiltonChapter 4: Lecture 16The Chemical Basis of Minerals(Perovskite & Spinels) Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300

  2. Perovskite CaTiO3 Structure CCP Orthorhombic 2/m2/m2/m, dipyramidal Structure of Mesosphere! Large A site cation Replaces ¼ of Oxygen Ti+4 octahedral Sharing apices

  3. Arborescent Perovskite CaTiO3 Stoltz Quarry, Graulai, Germany Graulai, Germany, Sephan Wolfsried Dysanalite (Nb,REE) Oka, PQ w/ Calcite & Monticellite P.Cristofono Ettringer-Bellerberg Mt.,Germany ~1mm - Stephan Wolfsried Lohley, Germany, Sephan Wolfsried

  4. Spinel AB2O4 Structure (~CCP) Oct Alternate layers parallel (111) Octahedral & Octahedral - Tetrahedral Oct & Tet Oct CCP with 1/8 Tetrahedral = A ¼ Octahedral = B Perpendicular to (111) after Waychunas (1991) Normal Spinel: B all Oct Inverse Spinel: B ½ Tet

  5. Spinel Structure (001) after Steven Dutch Layer 1 View along Four-fold Symmetry Axis (001 Plane) Layer 3 Filled octahedra form criss-cross rows with alternating layers of parallel rows offset as shown on the right side of the diagram. The square holes enclosed by the rows of octahedra are filled with tetrahedra

  6. Spinels: 2 Types of sub-unit cells Figure 1-b: Occupied octahedral site in spinel sub-cell b. B is in gray, and O is in red. Figure 2: Arrangement of structure a and b in one unit cell. shaded one represents structure a, while white one represents b. Figure 1-a: Two kinds of occupied tetrahedral sites in spinel sub-cell a. A is in green and O is in red. Gary Wulfsberg, Inorganic Chemistry, (2000)

  7. Normal Spinels: Spinel: MgAl2O4 Hercynite: FeAl2O4 Gahnite: ZnAl2O4 Franklinite: ZnFe+32O4 Chromite: FeCr2O4 Magnesiochromite MgCr2O4 LiMn2O4 Lithium battery Inverse Spinels: Magnetite: Fe+2Fe+32O4 Ulvospinel: Fe+22Ti+4O4 Ni+2Fe+32O4 Co+2Fe+32O4 Ferrofluids paramagnets Thiospinels: Greigite: Fe+2Fe+32S4 Cuprous Ferrites CuCr2S4 Spinel Formulae: A+2B+32O4 > (Y+4X+22O4 Olivine ~12% less dense: transition 360-610km) 0.8 < A < 1.1 Ang. (Mg, Fe, Mn, Zn, & Cu) & 0.75 < B < 0.9 Ang. (Ti, Fe, Al, & Co) Magnetospirillum magnetotacticum makes Greigite magnetosomes for navigation

  8. Named for ”Magnesia”, Greece C. Thompson Spinels: Mogok, Myanmar Rob Lavinsky 8mm Magnetite with Epidote Speen Ghar, Afghanistan Rob Lavinsky Franklinite, Sterling Hill with Zincite & Calcite M.Baum 1993 Chromite bands in serpentinized Dunite Sommergraben, Austria, Franz Bernhard Named for Ben Franklin & Franklin Furnace

  9. Greigite (Fe2+Fe3+2S4) infilling wood Calcite NGHP: Silt Krishna-Godarvi Basin

  10. Exsolution of Cubic “Fe-Ti Spinel”& Hexagonal Imeno-Hematite (Norway)

  11. Oxygen Linkages in Common Silicates Nesosilicates: Olivine Garnet, Zircon Kyanite (SiO4)-4 II-Inosilicates: Hornblende Arfvedsonite (Si4O11)-6 Sorosilicates: “Pyro” Lawsonite, Epidote Melilite, Hemimorphite Vesuvianite (Si2O7)-6 Phyllosilicates: Paragonite Kaolinite Polylithionite (Si2O5)-2 Cyclosilicates: Beryl Cordierite, Benitoite Tourmaline (Si6O18)-12 I-Inosilicates: Enstatite Acmite,Augite, Jadeite Wollastonite (Si2O6)-4 Tectosilicates: Quartz, Tridymite Coesite (SiO2)0

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