1. 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

2. Perovskite CaTiO 3 Structure CCP Orthorhombic 2/m2/m2/m, dipyramidal Ti +4 octahedral Sharing apices Large A site cation Replaces ¼ of Oxygen Structure of Mesosphere!

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

4. Spinel AB 2 O 4 Structure (~CCP) Alternate layers parallel (111) Octahedral & Octahedral - Tetrahedral Oct Oct & Tet Perpendicular to (111) after Waychunas (1991) CCP with 1/8 Tetrahedral = A ¼ Octahedral = B Normal Spinel: B all Oct Inverse Spinel: B ½ Tet

5. View along Four-fold Symmetry Axis (001 Plane) Spinel Structure (001) after Steven Dutch 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 Layer 1 Layer 3

6. Figure 1-a: Two kinds of occupied tetrahedral sites in spinel sub-cell a. A is in green and O is in red. 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. Spinels: 2 Types of sub-unit cells Gary Wulfsberg, Inorganic Chemistry, (2000)

7. Spinel Formulae: A +2 B +3 2 O 4 > (Y +4 X +2 2 O 4 Olivine ~12% less dense: transition 360-610km) Normal Spinels: Spinel: MgAl 2 O 4 Hercynite: FeAl 2 O 4 Gahnite: ZnAl 2 O 4 Franklinite: ZnFe +3 2 O 4 Chromite: FeCr 2 O 4 Magnesiochromite MgCr 2 O 4 LiMn 2 O 4 Lithium battery Inverse Spinels: Magnetite: Fe +2 Fe +3 2 O 4 Ulvospinel: Fe +2 2 Ti +4 O 4 Ni +2 Fe +3 2 O 4 Co +2 Fe +3 2O 4 Ferrofluids paramagnets Thiospinels: Greigite: Fe +2 Fe +3 2 S 4 Cuprous Ferrites CuCr 2 S 4 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. Franklinite, Sterling Hill with Zincite & Calcite M.Baum 1993 8mm Magnetite with Epidote Speen Ghar, Afghanistan Rob Lavinsky Named for ”Magnesia”, Greece Named for Ben Franklin & Franklin Furnace Spinels: Mogok, Myanmar Rob Lavinsky Chromite bands in serpentinized Dunite Sommergraben, Austria, Franz Bernhard C. Thompson

9. Greigite (Fe 2+ Fe 3+ 2 S 4 ) infilling wood NGHP: Silt Krishna-Godarvi Basin Calcite

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

11. Oxygen Linkages in Common Silicates Nesosilicates: Olivine Garnet, Zircon Kyanite (SiO 4 ) -4 Sorosilicates: “Pyro” Lawsonite, Epidote Melilite, Hemimorphite Vesuvianite (Si 2 O 7 ) -6 Cyclosilicates: Beryl Cordierite, Benitoite Tourmaline (Si 6 O 18 ) -12 I-Inosilicates: Enstatite Acmite, Augite, Jadeite Wollastonite (Si 2 O 6 ) -4 II-Inosilicates: Hornblende Arfvedsonite (Si 4 O 11 ) -6 Phyllosilicates: Paragonite Kaolinite Polylithionite (Si 2 O 5 ) -2 Tectosilicates: Quartz, Tridymite Coesite (SiO 2 ) 0