Classification of the Minerals • Non-Silicates • Silicates – Native Elements – Orthosilicates Descriptive Mineralogy – Halides – Sorosilicates – Sulfides – Cyclosilicates – Oxides – Chain Silicates Classification of Minerals – Hydroxides – Layer Silicates – Carbonates – Tektosilicates – Sulfates – Phosphates
Native Elements Native Elements: Metals • Fe, Co, Ni: Meteorites • Platinum Group: (Ru, Rh, Pd, Os, Ir, Pt): Mafic Igneous Rocks • Coinage metals: Cu, Ag, Au – Cu, Ag: Supergene Enrichments (Sulfide Oxidation) – Au: Low Temperature Hydrothermal, Placer
Supergene Copper Native Elements: non-metals
• Carbon: – Graphite: Metamorphic Rocks – Diamond: Kimberlites • Sulfur (+Se): – Salt Domes (Sulfate reduction),
– Volcanos (H2S oxidation) • Tellurium (Te) Telluride oxidation
1 Hydrothermal Silver Hydrothermal Gold
Halides: Sulfides Minerals with halogen anions
• Halite (NaCl) and Sylvite (KCl): Evaporites
• Fluorite (CaF2) Low temperature hydrothermal
• Cryolite (Na3AlF6): Pegmatite
Fe-S Diagram Fe Sulfides
• Fe: – Pyrite FeS2 – Marcasite FeS2 – Pyrrhotite Fe1-xS – Troilite FeS – Arsenopyrite FeAsS
2 Cu Sulfides Other Sulfides
• Cu Sulfides • Sphalerite ZnS
– Chalcocite Cu2S • Molybdenite MoS2 – Covellite CuS • Galena PbS • Cu-Fe Sulfides • Realgar AsS and Orpiment As2S3 – Chalcopyrite CuFeS2 • Arsenopyrite FeAsS – Bornite Cu5FeS4 • Stibnite Sb2S3 • Cinnabar HgS
Molybdenite MoS2 Galena PbS
Occurrence: Accessory in granites and pegmatites. Occurrence: Low temperature hydrothermal. Uses: Principal ore of Mo; major ore of Re Uses: Principal ore of Pb; major ore of Ag
Realgar AsS Orpiment As2S3
Occurrence: Low temperature hydrothermal. Occurrence: Low temperature hydrothermal. Uses: minor ore of As Uses: minor ore of As
3 Stibnite Sb2S3 Cinnabar HgS
Crystal System Cubic (HT) Point Group -43m Space Group F-43m Optical Color Dark Red Luster Adamantine Hardness 2.5 Occurrence: Low Density 8.10 temperature hydrothermal. Uses: Principal ore of Hg Occurrence: Low temperature hydrothermal. Uses: Principal ore of Sb
Simple Oxides Simple Oxides • Hemioxides • Sesquioxides – Cuprite (Cu2O) – Corundum (Al2O3) – Ice (H2O) – 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)
Ice H2O Hemi-Oxides (M2O)
• Ice (H2O) Hexagonal • Cuprite (Cu2O) • Why not Na2O? – (Na radius too large)
4 Monoxides (MO) • Rocksalt oxides MgO, FeO, MnO, Ice H2O CaO, NiO – Periclase MgO - Wuestite FeO – Manganosite MnO High – Lime CaO Pressure – Bunsenite NiO Phase • Zincite oxides: zincite ZnO, Diagram bromellite BeO • Other monoxides: – Tenorite CuO, Montroydite HgO
Periclase Structure
Periclase MgO
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 Color Colorless Cr2O3 Luster Vitreous • Other Sesquioxides Hardness 9 – Bixbyite Mn2O3 Density 4.02
5 Corundum Al2O3 Dioxides
• Rutile Group – Rutile TiO2; Anatase; Brookite – Cassiterite SnO2 – Pyrolusite MnO2 – Stishovite SiO2 • Uraninite (UO2) and Thorianite (ThO2) • Baddeleyite ZrO2
Rutile TiO2 Complex Oxides Pyrolusite MnO2 Cassiterite SnO 2 • Two or more different cations Stishovite SiO2 – Spinel Group: M2TO4 – Ilmenite Group : FeTiO3 – Pseudobrookite Group : A2BO5 – Perovskite Group : CaTiO3 • High Pressure silicate analogues
Spinel Structure Spinel Group Space Group Fd3m • Spinel MgAl2O4 • Magnesioferrite Edge sharing • Hercynite FeAl2O4 MgFe2O4 octahedra • Chromite FeCr2O4 • Gahnite ZnAl2O4 Cell edge ~8.5Å • Magnesiochromite • Ulvospinel TiFe2O4 Two octahedra per MgCr2O4 • Ringwoodite Mg2SiO4 • Magnetite Tetrahedron 2+ 3+ Fe Fe 2O4 Mg Al 2 O 4 (Normal) or
Al (MgAl) O4 (Inverse)
6 Ilmenite Structure Ilmenite Group • Corundum Structure • Ilmenite FeTiO 3 • Space Group R-3 • Geikielite MgTiO3 • Alternating • Akimotoite MgSiO3 layers of Fe and Ti Octahedra • Face-sharing Octahedra • Dense
Pseudobrookite Pseudobrookite Group Structure • Pseudobrookite Fe2+Ti2O5 • Space • Ferro-pseudobrookite TiFe3+2O5 Group Bbmm • Armalcolite (Mg,Fe2+)Ti2O5 • M1 dark • M2 lighter
Perovskite Structure Perovskite
• Pseudo- • Perovskite CaTiO3 cubic • MgSiO3 (Lower mantle phase) • Orthorhom bic • Space Group Pbnm
7 Accessory Oxides Hydroxides
• Brucite Mg(OH)2
• Gibbsite Al(OH)3 • Boehmite and Diaspore AlO(OH) • Bauxite (Mixed Al hydroxides) • Goethite FeO(OH) (+Lepidochrosite)
• Limonite Fe(OH)3
Dioctahedral vs. Trioctahedral Carbonates
• Calcite Group • Aragonite Group • Dolomite Group • Other carbonates
Calcite Group
• Calcite CaCO3 • Magnesite MgCO3 • Siderite FeCO3 • Rhodochrosite MnCO3 • Smithsonite ZnCO3
8 Calcite Structure Aragonite Group
• Space • Aragonite CaCO Group R-3c 3 • Strontianite CaCO3 • Divalent • Witherite BaCO3 cation • Cerussite PbCO3 radius < 1.00Å
Aragonite Structure Dolomite Group • Space Group Pbnm • Dolomite CaMg(CO3)2 • Cation • Ankerite CaFe(CO3)2 Radius > 1.00Å
Other Carbonates Sulfates (+Nitrates)
• Malachite (Green) Cu2(OH)2CO3 • Gypsum CaSO4•2H2O
• Azurite (Blue) Cu3(OH)2(CO3)2 • Anhydrite CaSO4 – Cu1+ or Cu 2+? • Celestine SrSO4
• Bastnasite REECO3F • Barite BaSO4
• Niter KNO3 • Anglesite PbSO4
• Soda Niter NaNO3 • Alunite KAl3(OH)6(SO4)2
9 Gypsum Anhydrite
• CaSO4•2H2O • CaSO4 • Hardness 2 • Hardness 3-3.5 • Evaporite • Evaporite Mineral Mineral • Contains • Contains no molecular water molecular water
Celestine Barite Anglesite
• SrSO4 BaSO4 PbSO4 • Hydrothermal Hydrothermal OxHydrothermal •
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