12/1/2012 Classification of the Minerals Descriptive Mineralogy • Non-Silicates • Silicates – Native Elements – Orthosilicates – Halides – Sorosilicates – Sulfides – Cyclosilicates Oxides and – Oxides – Chain Silicates – Hydroxides – Layer Silicates Hydroxides – Carbonates – Tektosilicates – Sulfates – Phosphates Simple Oxides Simple Oxides • Hemioxides • Sesquioxides – Cuprite (Cu O) 2 – Corundum (Al2O3) – Ice (H O) 2 – Hematite (Fe2O3) • Monoxides – Bixbyite (Mn2O3) – Periclase (MgO) • Dioxides – Wüstite (FeO) – Rutile (TiO2) – Manganosite (MnO) – Anatase (TiO2) – Lime (CaO) – Brookite (TiO2) – Zincite (ZnO) – Cassiterite(SnO2) – Bromellite (BeO) – Pyrolusite(MnO2) – Tenorite (CuO) Hemi-Oxides (M2O) Hemi-Oxides (M2O) • Ice (H2O) Hexagonal • Na2O occurs as a mineral • Cuprite (Cu2O) • Why not Na2O? – A. True – Na radius too large – B. False – Na has no covalent orbitals available 1 12/1/2012 Cuprite Cu2O Cuprite Cu2O • Occurrence: Low • Occurrence: Low Temp Temp Hydrothermal Hydrothermal (Supergene) (Supergene) • Use: Minor ore of Cu • Strongly covalent •O SP3 •Cu SP • Use: Minor ore of Cu Ice H2O Ice H2O Crystal System Hexagonal Point Group 6/mmm Space Group P63/mmc Optical Uniaxial Color Colorless Luster Vitreous Hardness 1.5 Density 0.95 Ice H2O snow morphology Ice H2O High Pressure Phase Diagram 2 12/1/2012 Ice H2O What’s Wrong Here? Monoxides (MO) Rocksalt Oxides • Rocksalt oxides MgO -FeO -MnO -CaO – Periclase MgO - Wüstite FeO – Manganosite MnO Crystal System Cubic – Lime CaO Point Group 4/m-32/m – Bunsenite NiO • Zincite oxides: Space Group Fm3m Optical Isotropic – Zincite ZnO, – Bromellite BeO • Other monoxides: – TenoriteCuO, Montroydite HgO Periclase - Wüstite MgO - FeO Periclase MgO Lower mantle phase Mg2SiO4 = MgSiO3 + MgO Ringwoodite = Perovskite + periclase 3 12/1/2012 Zincite Group Other Monoxides ZnO – Zincite, CuO – Tenorite BeO Bromellite HgO Montroydite Crystal System Hexagonal Point Group 6mm Oxidized hydrothermal deposits Space Group P63mc Optical Uniaxial Extreme Piezoelectric Covalent Bonding Uses: Transducers Irregular coordination Corundum Al2O3 Sesquioxides (M2O3) Crystal System Trigonal • Corundum Group Point Group -32/m – Corundum Al2O3 Space Group R-3c – Hematite Fe2O3 Optical Uniaxial – Karelianite V2O3 and Eskolaite Cr2O3 Color Colorless • Other Sesquioxides Luster Vitreous – Bixbyite Mn2O3 Hardness 9 Density 4.02 Corundum Al2O3 Corundum Al2O3 4 12/1/2012 Hematite Fe2O3 Hematite Fe2O3 Crystal System Trigonal Point Group -32/m Space Group R-3c Optical Nearly opaque Color Red/Metallic Luster Earthy/metallic Hardness 6 Density 5.26 Bixbyite Mn2O3 Dioxides Crystal System Cubic • Rutile Group Point Group 4/m-32/m – Rutile TiO2; Anatase; Brookite Space Group Ia3 – Cassiterite SnO2 Optical Nearly opaque – Pyrolusite MnO2 Color Red/Metallic – Stishovite SiO2 Luster Earthy/metallic • Uraninite (UO2) and Thorianite Hardness 6 (ThO2) Density 4.95 • Baddeleyite ZrO2 Rutile TiO Rutile TiO2 2 Pyrolusite MnO2 Crystal System Tetragonal Cassiterite SnO2 Point Group 4/mmm Stishovite SiO2 Space Group P42/mnm Optical Nearly opaque Color Red Luster Adamantine Hardness 6 Density 4.23 5 12/1/2012 Anatase and Brookite TiO 2 Cassiterite SnO2 Uraninite UO2 Uraninite UO2 Crystal System Cubic The Major ore of U Point Group 4/m-32/m U4+ or U6+? Space Group Fm-3m Same structure as fluorite Optical Nearly opaque U6+ is soluble U4+ is insoluble Color Black U is mobilized by oxidation; immobilized by reduction Luster Submetallic Roll-front deposits. Hardness 5.5 Natural reactors Density 7-9 Occurrence Lo T Hyd Roll-front Use: Major Ore of U Simple Oxides Complex Oxides • Two or more different cations – Spinel Group: M2TO4 – Ilmenite Group : FeTiO3 – Pseudobrookite Group : A2BO5 – Perovskite Group : CaTiO3 • High Pressure silicate analogues 6 12/1/2012 Spinel Group Spinel Structure • Spinel MgAl2O4 Space Group Fd3m • Hercynite FeAl2O4 Edge sharing • Chromite FeCr2O4 octahedra • Magnesiochromite MgCr2O4 Cell edge ~8.5Å 2+ 3+ • Magnetite Fe Fe 2O4 Two octahedra per • Magnesioferrite MgFe2O4 Tetrahedron • Gahnite ZnAl2O4 MgAl2O4 (Normal) • Ulvospinel TiFe2O4 or • Ringwoodite Mg2SiO4 Al (MgAl) O4 (Inverse) Ringwoodite γ (spinel) -(MgFe)2SiO4 Ilmenite Group • Ilmenite FeTiO3 • Dark blue • Geikielite MgTiO3 color • Akimotoite MgSiO3 • 525 – 660km • ~5% Earth Ilmenite Structure FeTiO3 Pseudobrookite Group • Corundum Structure • Space Group R-3 • Pseudobrookite Fe2+Ti2O5 • Alternating • Ferro-pseudobrookite TiFe3+2O5 layers of Fe and • Armalcolite (Mg,Fe2+)Ti2O5 Ti Octahedra • Face-sharing Octahedra • Dense 7 12/1/2012 Accessory Oxides Pseudobrookite Structure • Space Group Bbmm • M1 dark • M2 lighter • Open Structure Accessory Oxides Perovskite • Perovskite CaTiO3 • MgSiO3 (Lower mantle phase) Perovskite Structure Hydroxides • Pseudo-cubic • Brucite Mg(OH)2 • Orthorhombic • Gibbsite Al(OH)3 • Space Group • Boehmite and Diaspore AlO(OH) Pbnm • Bauxite (Mixed Al hydroxides) • Goethite FeO(OH) (+Lepidochrosite) • Limonite Fe(OH)3 8 12/1/2012 Gibbsite Al(OH)3 Brucite Mg(OH)2 Di-octahedral Tri-octahedral • Two out of • All three three possible possible octahedral octahedral sites sites occupied occupied • Divalent • Tri-valent cations cations 9.