GY 302: Crystallography & MineralogyGY 302: Crystallography & MineralogyUNIVERSITY OF SOUTH ALABAMALecture 15: Carbonates, Nitrates, BoratesLecture 15: Carbonates, Nitrates, BoratesLast TimeHalidesSelect mineralsOccurrences and Associations Featured minerals: EvaporitesHalite (NaCl)Crystal: IsometricPt. Group: 4/m 3 2/mHabit: cubic, hopper crystalsSG: 2.17; H: 2.5 L: vitreous; Str: whiteCol: white (various shades)Clev: perfect [100], [010], [001]Optics: Isotropic (n=1.544)─Name derivation: From the Greek halos (salt) Halide MineralsFluorite (CaFFluorite (CaF22))Crystal: IsometricPt. Group: 4/m 3 2/mHabit: cubic, octahedral crystalsSG: 3.0-3.25; H: 4 L: vitreous; Str: whiteCol: variableClev: [111] perfectOptics: Isotropic (n=1.434)─Name derivation: From its elemental composition containing fluorName derivation: From its elemental composition containing fluorineineHalide Mineralshttp://www.electric-lady-land.com/004.%20Fluorite-LW.jpgEvaporite FormationFirst LastAragonite (ooids) Dolomite Gypsum Anhydrite Halite Sylvite*Today’s AgendaCarbonates, Nitrates, Borates 1. Select carbonate minerals2. Sphalerite and galena (left over sulfides) Featured mineral association: MVT-ores(Mississippi Valley-type ores)Carbonates, Nitrates, BoratesCarbonates, Nitrates, Borates•There are 70 carbonate minerals, over 60 borates and a few nitratesCarbonates, Nitrates, Borates•There are 70 carbonate minerals, over 60 borates and a few nitrates•All 3 types of minerals involve planar anion groups….•… with the exception of BO44-which is tetrahedralCarbonates, Nitrates, Borates•There are 70 carbonate minerals, over 60 borates and a few nitrates•All 3 types of minerals involve planar anion groups….•… with the exception of BO44-which is tetrahedral•Oxygen atoms are strongly covalently bonded in the anion (especially in CO32-), but bonding between the anion and the cation is ionicCarbonates, Nitrates, Borates•Carbonates are by far the most important of the Class V minerals, three of which (calcite, dolomite and aragonite) comprise about 40% of all sedimentary rocks and more than 20% of the entire geological column.•They are both biogenic and chemically precipitatedCarbonatesCalcite Group (3 2/m): Calcite (CaCO3)Magnesite (MgCO3)Siderite (FeCO3)Rhodochrosite (MnCO3)Smithsonite (ZnCO3)CarbonatesCalcite Group (3 2/m): Calcite (CaCO3)Magnesite (MgCO3)Siderite (FeCO3)Rhodochrosite (MnCO3)Smithsonite (ZnCO3)Dolomite Group (3): Dolomite (CaMg(CO3)2)Ankerite (CaFe(CO3)2)Kutnahurite (CaMn(CO3)2)Zincian Dolomite (CaZn(CO3)2)CarbonatesCalcite Group (3 2/m):Calcite (CaCO3)Magnesite (MgCO3)Siderite (FeCO3)Rhodochrosite (MnCO3)Smithsonite (ZnCO3)Dolomite Group (3): Dolomite (CaMg(CO3)2)Ankerite (CaFe(CO3)2)Kutnahurite (CaMn(CO3)2)Zincian Dolomite (CaZn(CO3)2)Calcite and Dolomite both possess 6-fold (Octahedral) coordinationThe only difference is that dolomite lacks 2/m symmetry because of alternating Ca-Mg layersCarbonatesCalcite Group (3 2/m): Calcite (CaCO3)Magnesite (MgCO3)Siderite (FeCO3)Rhodochrosite (MnCO3)Smithsonite (ZnCO3)Aragonite Group (2/m 2/m 2/m): Aragonite (CaCO3)Witherite (BaCO3)Strontianite (SrCO3)Cerussite (PbCO3)Calcite (CaCO3)Crystal: Hexagonal (Trigonal)Pt. Group: 3 2/mHabit: euhedral (rhombs); scalenohedral (“dog tooth”), bladed, stalactitic, massiveSG: 2.71; H: 3 L: vitreous, waxy; Str: whiteCol: white (various shades)Clev: {101} PerfectOptics: uniaxial -ne= 1.486; nw= 1.658─Name derivation: From the Latin, calx, meaning limeCarbonate MineralsCalcite (CaCO3)Occurrence: widespread sedimentary and epithermal breccia (MVT) deposits; biogenic mineral (trilobites, echinoderms etc.)Associated Mins: sedimentary: dolomite, aragonite, quartz; MVT: dolomite, sphalerite, galena, fluoriteMay be confused with:most rhombohedralcarbonates (possibly distinguished because of its reactivity with HCl)Uses:manyCarbonate MineralsCalcite is used for:1) Polarizing filters in optics (Iceland spar)2) a flux in steel manufacturing3) building materials, floor tiles, marble vanities4) Portland cementCarbonate MineralsCalcite is used for:1) Polarizing filters in optics (Iceland spar)2) a flux in steel manufacturing3) building materials, floor tiles, marble vanities4) Portland cementCarbonate MineralsCaCO3CaOheat<10% Mg0% PyriteCalcite is used for:1) Polarizing filters in optics (Iceland spar)2) a flux in steel manufacturing3) building materials, floor tiles, marble vanities4) Portland cementCarbonate MineralsCaCO3CaO + clay “clinker”burnedCalcite is used for:1) Polarizing filters in optics (Iceland spar)2) a flux in steel manufacturing3) building materials, floor tiles, marble vanities4) Portland cementCarbonate MineralsCaCO3CaO + clay “clinker”Water + sand+gravel“concrete”Dolomite (CaMg(CO3)2)Crystal: Hexagonal (trigonal)Pt. Group: 3Habit: euhedral rhombohedral, saddlesSG: 2.86; H: 3.5 L: vitreous; Str: whiteCol: white to grey, pinkClev: {101} PerfectOptics: uniaxial -ne= 1.500; nw= 1.680─Name derivation: French mineralogist Deodat Guy Tancrede Gratet de Dolomieu (1750-1801)Carbonate MineralsDolomite (CaMg(CO3)2)Occurrence: widespread sedimentary and epithermal breccia (MVT) deposits, replacement mineral, synsedimentary sabkhadeposits (pseudo-dolomite)Associated Mins: sedimentary: calcite, gypsum, anhydrite, aragonite; MVT: calcite, sphalerite, galena, fluoriteMay be confused with:most rhombohedralcarbonates Uses:agricultureCarbonate MineralsAragonite (CaCO3)Crystal: Orthorhombic (pseudo hexagonal)Pt. Group: 2/m 2/m 2/mHabit: euhedral, hexagonal prismsSG: 2.94; H: 3.5-4L: vitreous; Str: whiteCol: colourless (pinkish)Clev: poor{010}, {110}Optics: Biaxial -nα= 1.530; nβ= 1.682; nγ= 1.686Name derivation: From its type location, Aragon in SpainCarbonate MineralsAragonite (CaCO3)Occurrence: blueschist metamorphic facies; common biogenic mineral (corals, bivalves, etc.)Associated Mins: metamorphic assemblage: glaucophane, pumpellyiteMay be confused with:calciteUses:noneCarbonate MineralsCalcite-Aragonite stability fieldhttp://www.geol.lsu.edu/henry/Geology3041/lectures/26MetaReactions/Fig26-1.jpgRhodochrosite (MnCO3)Crystal: Hexagonal (Trigonal)Pt. Group: 3 2/mHabit: botryoidal, banded, euhedral (rhombs); massiveSG: 3.69; H: 4 L: vitreous, waxy; Str: whiteCol: pink, pinkish red, yellowClev: {101} PerfectOptics: uniaxial -ne= 1.596; nw= 1.816─Name derivation: From the Greek rhodon for rose and chroma for color.Carbonate MineralsRhodochrosite