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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 13 The Chemical Basis of Minerals (Parsimony & Isostructural Minerals). Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300. #5 - Principle of Parsimony.

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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 13The Chemical Basis of Minerals(Parsimony & Isostructural Minerals) Camosun College GEOS 250 Lectures: 9:30-10:20 M T Th F300 Lab: 9:30-12:20 W F300

  2. #5 - Principle of Parsimony • # of contrasting elements are small because there are few anion or cation sites • Complex compositions tend toward several constituents (cations) in the same kind of site • This is termed solid solution: Fe for Mg, Si for Al, Ca for Na (definite not exact compositions) • Goldschmidt’s rules say ions have to be similar size +/-15% and +/- 1 charge unit

  3. Limited Types of Coordination Halite Octahedral – Na & Cl Octahedral – Ca Tetrahedral – F Fluorite Sphalerite Octahedral – empty Tetrahedral - S

  4. Halite: Hesse, Germany S. Menig 2005, Saskatchewan Rob Levinsky 4/m 3 2/m Hexoctahedral Cubes Cubic cleavage on (001) Halite named by J.D. Dana for Greek αλς “sea” Evaporite deposits, Salt domes Bedded sediments Muhlhausen Alsace, France John Betts 2002; Christopher O’Neill

  5. Fluorite: Rogerly Mine, Weardale, Durham Co. Pennines Wales, Jesse Fisher 2001 4/m 3 2/m Hexoctahedral Cubes with Penetration twins (111) Cleavage octahedral Tetrahexahedron Nilaw-Kolum Afghanistan Fabre Minerals The term fluorescence is derived from fluorite, which will often exhibit this effect when Y & Ce Substitute for Ca ions Ore of Fluorine Production of HF Flux in Steel & Glass Greisens, Granites Pegmatites & Gangue in Hi T Pb-Zn ores Octahedra Catamarca Argentina J.C. Lodovici

  6. Mineral Names - Trivial Pursuits! Halite – Greek, halos for salt, mineral of health Fluorite – Latin fleure to flow, melts easily, flux Sphalerite – Greek treacherous,zincblende, German “blind”, decieving,rubyzinc or blackjack

  7. Sphalerite:43m Hextetrahedral v.Marmatite Elmwood Mine TN, John Betts 2003 var. Ruby-blende, Taz. Aus.R. Bottrill 2006 CdS Greenockite coating, Tazmania, viccloete

  8. Sphalerite • Think about those empty octahedra of Zn! • X3 to x10 thermal and electrical conductivity compared to other sulphides • With Fe substitution, darkens (blackjack), reflects more & enhances magnetic susceptibility • w/ Pyrrhotite Fe1-xS, Fe-Zn a geothermometer, • Main ore of Cd, isostructural w/Greenockite CdS • alters to Goslarite ZnSO3 or Smithsonite ZnCO3

  9. Parsimony - Complex compositions tend toward several constituents (cations) in the same kind of site • Monoclinic Amphiboles: • Hornblende, Richterite, Actinolite, Tremolite, Glaucophane, Riebeckite • (Ca,Na)2-3(Mg,Fe,Al)5Si6(Si,Al)2O22(OH)2 • For chemical calculations sometimes O23

  10. Amphibole Polyhedral SitesProjected along a - axis T2 Mg Fe, Mn Si+4 , Al+3 Ca+2 , K+ Al+3 , Fe+3 Ti+4 Ca+2 , Na+ J.J Papike, 1969

  11. Riebeckite:[ ][Na 2][Fe2+3Fe3+2][(OH)2][Si8O22] Golden Horn Batholith, Washington Pass, ROM Richterite: Na[CaNa][Mg5][(OH)2][Si8O22] Mt. Ngongotaha Rotorua NZ Magnesiohornblende: [Ca2][Mg4Al][(OH)2][AlSi7O22] Eifel Mtns Rhineland Germany J. Weissmann 2008 Chromian Tremolite: [Ca2][Mg5][(OH)2][Si8O22] Haliburton ON John Betts 2001

  12. Isostructural Minerals • UO2 & CaF2 (Uraninite & Fluorite, Oct/Tet) (different in solutions, Linear & Oct/Cubic, different energy or they wouldn’t dissolve!) • NaClHalite & MgOPericlase & PbSGalena & MnSAlabandite & AgClChlorargyrite & TiNOsbornite (named after Donny & Marie?) • StishoviteSiO2 & RutileTiO2 are both octahedral, for Silicon this takes GPa’s of P • Isostructural Groups: Barite (sulphates), Calcite (Carbonates) Aragonite (Carbonates)

  13. Uraninite & Gummite Great Bear Lake, NWT M Arliguie UO2 Haliburton ON John Betts 2001 Uraninite radiation damage halo Parfurbwirt, Austria Chris Auer, 1984

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