Lecture 18 (11/29/2006) Systematic Description of Minerals Part 2: Oxides, Hydroxides Halides, Carbonates, Sulfates, and PhosphatesOxidesFe-Ti oxidesSpinel Group (XY2O4)Other Common OxidesHydroxidesCommon Types of HydroxidesHalidesCommon HalidesMineral Groups formed with Anionic ComplexesCarbonatesOther CarbonatesBoratesSulfatesTungstates & MolybdatesPhosphatesOther Common PhosphatesNext Lecture 11/29/06Lecture 18 (11/29/2006)Lecture 18 (11/29/2006)Systematic Description of MineralsSystematic Description of Minerals Part 2:Part 2: Oxides, Hydroxides Halides, Oxides, Hydroxides Halides, Carbonates, Sulfates, and Carbonates, Sulfates, and PhosphatesPhosphatesOxidesOxidesThree main groups based on metal cation/oxygen ratiosThree main groups based on metal cation/oxygen ratiosHematite GroupHematite Group (X (X22OO33) ) Corundum X=AlCorundum X=Al+3+3 most phases hexagonal most phases hexagonal Hematite X=FeHematite X=Fe+3+3Ilmenite X=1FeIlmenite X=1Fe+2+2+1Ti+1Ti+4+4Rutile GroupRutile Group (XO (XO22))Rutile X=TiRutile X=Tix- +4 cationx- +4 cationPyrolusite X=MnPyrolusite X=Mnmost phases tetragonalmost phases tetragonalCassiterite X=SnCassiterite X=SnUraninite X=UUraninite X=USpinel GroupSpinel Group (XY (XY22OO44))Spinel X=Mg, Y=AlSpinel X=Mg, Y=AlX- +2X- +2; Y- +3 cation; Y- +3 cationMagnetite X=FeMagnetite X=Fe+2+2, Y=Fe, Y=Fe+3+3most phases isometricmost phases isometric Chromite X=FeChromite X=Fe+2+2, Y=Cr, Y=Cror orthorhombicor orthorhombicChrysoberyl X=Be, Y=AlChrysoberyl X=Be, Y=AlUlvospinel X=TiUlvospinel X=Ti+4+4, Y=Fe, Y=Fe+2+2Fe-Ti oxidesFe-Ti oxidesFeFe+2+2FeFe+3+3Spinel Group Spinel Group (XY(XY22OO44)) Gem-quality Gem-quality SpinelsSpinelsOther Common OxidesOther Common OxidesRutile (TiORutile (TiO22))Rutile needles in Rutile needles in QuartzQuartzPyrolusite dendritesPyrolusite dendriteson fracture faceson fracture facesPyrolusite (MnOPyrolusite (MnO22))Mass of botryoidal Mass of botryoidal PyrolusitePyrolusiteCorundum (AlCorundum (Al22OO33))Hardness=9Hardness=9Red = RubyRed = RubyBlue = SapphireBlue = SapphireChrysoberyl (BeAlChrysoberyl (BeAl22OO44))Cyclic twinningCyclic twinningin Chrysoberylin ChrysoberylHydroxidesHydroxides(OH)(OH)- - main anionic group forming octahedrally main anionic group forming octahedrally coordinated sheets with weak bonds betweencoordinated sheets with weak bonds betweenTwo structural types: Two structural types: Brucite-typeBrucite-type – trioctahedral – trioctahedral sheets (all octahedral cation sheets (all octahedral cation sites are filled)sites are filled)Gibbsite-typeGibbsite-type – dioctahedral – dioctahedral sheets (only two of three sheets (only two of three octahedral sites are filled)octahedral sites are filled)Common Types of HydroxidesCommon Types of HydroxidesBrucite Brucite Mg(OH)Mg(OH)22 Gibbsite Gibbsite Al(OH)Al(OH)33Manganite Manganite MnO(OH)MnO(OH) DiasporeDiasporeAlO(OH)AlO(OH)GoethiteGoethiteFeO(OH)FeO(OH) Bauxite Bauxite Al-hydroxide* Al-hydroxide**hybrid mix of diaspore, gibbsite, and boehmite (*hybrid mix of diaspore, gibbsite, and boehmite (AlO(OH))AlO(OH))HalidesHalidesSimple compounds composed of Simple compounds composed of large halogen anions (Cl, Br, F, I)large halogen anions (Cl, Br, F, I)Typically isometricTypically isometricDominantly ionic bondingDominantly ionic bondingProperties – low hardness, high Properties – low hardness, high melting points, poor conductors melting points, poor conductors (except at high temperatures)(except at high temperatures)Common Halides Common Halides Halite (NaCl)Halite (NaCl)Sylvite (KCl)Sylvite (KCl)Flourite (CaFFlourite (CaF22))Mineral Mineral Groups Groups formed with formed with Anionic Anionic ComplexesComplexesCarbonatesCarbonatesSulfatesSulfatesPhosphatesPhosphatesSilicatesSilicatesAmount of residual chargeAmount of residual chargeindicates relative strength indicates relative strength bonds with cations, which bonds with cations, which reflected in the hardness reflected in the hardness of the mineralof the mineralCarbonatesCarbonatesAragoniteAragonite(High-P) Orthorhombic(High-P) OrthorhombicCalciteCalcite(Low-P - Hexagonal)(Low-P - Hexagonal)Most are Hexagonal Most are HexagonalOther CarbonatesOther CarbonatesAzurite - CuAzurite - Cu33(CO(CO33))22(OH)(OH)2 2 (Blue)(Blue)Malachite – CuMalachite – Cu22COCO33(OH)(OH)22 (Green) (Green)Rhodochrosite – MnCORhodochrosite – MnCO33BoratesBoratesKernite – NaKernite – Na22BB44OO66(OH)(OH)22·3H·3H22OOBorax - NaBorax - Na22BB44OO55(OH)(OH)44·8H·8H22OOUlexite – NaCaBUlexite – NaCaB55OO66(OH)(OH)66·5H·5H22OOH – 2-2.5; SG – 1.7H – 2-2.5; SG – 1.7H – 3; SG – 1.95H – 3; SG – 1.95H – 1-2.5; SG – 1.96H – 1-2.5; SG – 1.96““Television Rock”Television Rock”SulfatesSulfatesHYDROUS HYDROUS ANHYDROUSANHYDROUSGypsum – CaSOGypsum – CaSO44·2H·2H22OOAlunite – KAlAlunite – KAl33(SO(SO44))22(OH)(OH)66Barite – BaSOBarite – BaSO44Anhydrite – CaSOAnhydrite – CaSO44H: 3-3.5H: 3-3.5SG: 4.5SG: 4.5H: 3-3.5H: 3-3.5SG: 2.9SG: 2.9H: 2H: 2SG: 2.32SG: 2.32H: 4H: 4SG: ~2.7SG: ~2.7Tungstates & MolybdatesTungstates & MolybdatesWoframite – (Fe,Mn)WOWoframite – (Fe,Mn)WO44Scheelite – CaWOScheelite – CaWO44Wulfenite – PbMoOWulfenite – PbMoO44SG: 7-7.5SG: 7-7.5SG: ~6SG: ~6SG: 6.8SG: 6.8PhosphatesPhosphates Apatite – CaApatite – Ca55(PO(PO44))33(F,Cl,OH)(F,Cl,OH)–prismatic hexagonal crystalsprismatic hexagonal crystals–common in igneous rocks and common in igneous rocks and hydrothermal depositshydrothermal deposits- variable colors- variable colorsOther Common PhosphatesOther Common PhosphatesMonazite – (Ce,La,Y,Th)POMonazite – (Ce,La,Y,Th)PO44Ore mineral for Rare Earth ElementsOre mineral for Rare Earth ElementsUseful mineral in U-Pb and Th age datingUseful mineral in U-Pb and Th age datingWavellite – AlWavellite – Al33(PO(PO44))22(OH)(OH)33·5H·5H22OORadiating globular aggregatesRadiating globular aggregatesTurquoise – Turquoise – CuAlCuAl66(PO(PO44))44(OH)(OH)88·5H·5H22OONext Lecture 11/29/06Next Lecture 11/29/06 Systematic Description of MineralsSystematic Description of Minerals Part 3: Silicates Part 3: SilicatesRead: Klein Chap. 11Read: Klein Chap.