GY 302: Crystallography & MineralogyGY 302: Crystallography & MineralogyUNIVERSITY OF SOUTH ALABAMALecture 16: Sulfates and Phosphates(Class VI and VII Minerals)Lecture 16: Sulfates and Phosphates(Class VI and VII Minerals)Last time (before the test)Carbonates, Nitrates, Borates 1. Select carbonate minerals2. Sphalerite and galena (left over sulfides) Featured mineral association: MVT-ores(Mississippi Valley-type ores)Carbonates, 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 ionicCarbonatesCalcite 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)Aragonite Group (2/m 2/m 2/m): Aragonite (CaCO3)Witherite (BaCO3)Strontianite (SrCO3)Cerussite (PbCO3)Aragonite (CaCO3)Crystal: Orthorhombic (pseudo hexagonal)Pt. Group: 2/m 2/m 2/mHabit: euhedral, hexagonal prismsSG: 2.94; H: 3.5-4 L: 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 MineralsMVT-oresMississippi Valley-type ore deposits•Named after the type mines in Missouri, Tennessee and other sites in the Mississippi Valley•Low temperature (epithermal) sedimentary ore deposits•Primary minerals produced: dolomite (saddle), calcite, fluorite and some old friends….Today’s AgendaSulfates and Phosphates1. Class VI Minerals: Sulfates, Chromates, Molybdates, Tungstates2. Class VII Minerals: Phosphates, Arsenates and Vanadates3. Economics of Class VII mineralsSulfates etc.Gypsum (CaSO4·2H2O)Crystal: MonoclinicPt. Group: 2/mHabit: massive, fibrous, vitreous, sand crystalsSG: 2.3; H: 2 L: vitreous to dull; Str: whiteCol: colorless to greyClev: perfect {010}, weak {100}, {111}Optics: Biaxial +nα= 1.520; nβ= 1.522; nγ= 1.529Name derivation: From the Greek, gyps meaning "burned" mineral. Selenite from the Greek in allusion to its pearly luster (moon light) on cleavage fragments.Sulfate Mineralshttp://www.soes.soton.ac.ukGypsum (CaSO4·2H2O)Occurrence: evaporite mineral; classic sabkha depositAssociated Mins: anhydrite, halite, dolomite (evaporites)Can be confused with:ulexite (satin spar)Uses:building materialsSulfate MineralsAnhydrite (CaSO4)Crystal: OrthorhombicPt. Group: 2/m 2/m 2/mHabit: massive, fibrous (rare)SG: 2.97;H: 3.5L: vitreous to dull; Str: whiteCol: colorless to greyClev: perfect [010]. [100], good [001]Optics: Biaxial +nα= 1.570; nβ= 1.576; nγ= 1.614Name derivation: Greek anhydros, meaning "waterless"Sulfate MineralsAnhydrite (CaSO4)Occurrence: evaporite mineral (related to gypsum), less common in granite ore bodies and altered igneous rocks (“gangue”)Associated Mins: gypsum, halite, dolomite (evaporites); zeolites in altered igneous rocksCan be confused with:dolomite, calcite, gypsum, bariteUses:building materialsSulfate MineralsCelestine/Celestite (SrSO4)Crystal: OrthorhombicPt. Group: 2/m 2/m 2/mHabit: euhedral blocky crystals commonSG: 4.0; H: 3 to 3.5 L: vitreous; Str: whiteCol: colorless to blueClev: perfect [001]; good [210]Optics: Biaxial +nα= 1.622; nβ= 1.624; nγ= 1.631Name derivation: Latin coelestis, meaning “celestial"Sulfate MineralsCelestine/Celestite (SrSO4)Occurrence: sedimentary deposits (associated with evaporite minerals) and in epithermal vein deposits. Rarer as a cave precipitate.Associated Mins: gypsum, halite, dolomite (evaporites), sulfur, fluoriteCan be confused with:bariteUses: principle source of strontiumSulfate MineralsWulfenite (PbMoO4)Crystal: TetragonalPt. Group: 4/mHabit: euhedral tabular crystalsSG: 6.75; H: 3L: vitreous; Str: yellowish-whiteCol: orange to yellowClev: poor [101]Optics: uniaxial -ne= 2.304; nw= 2.402Name derivation: Named after the Austrian mineralogist, Frantz Xaver von Wulfen (1728-1805) Molybdate MineralsWulfenite (PbMoO4)Occurrence: secondary (supergene?) product in lead and molybdenum sulfide ore deposits Associated Mins: pyromorphite, vanadinite, calciteCan be confused with:vanadiniteUses:secondary source of MoMolybdate MineralsPhosphates etc.Apatite Group (Ca5(PO4)3(F,Cl,OH)Fluorapatite (Ca5(PO4)3(F) Crystal: HexagonalPt. Group: 6/mHabit: hexagonal crystals common, massiveSG: 3.19; H: 5L: vitreous; Str: whiteCol: you name it, you’ll see itClev: indistinctOptics: uniaxial -ne= 1.630; nw= 1.633Name derivation: Greek apatao, meaning “misleading"Phosphate MineralsApatite (Ca5(PO4)3(F,Cl,OH)Occurrence: common. Igneous rocks, metamorphic rocks, crusts in altered biogenic remains (guano + coral)Associated Mins: varied (reflects wide occurrence)Can be confused with:beryl, corundum; diopside and olivine when massiveUses:primary mineral source of phosphorus (fertilizer)Phosphate MineralsWavellite (Al3(PO4)2(OH)3·2H2O)Crystal: OrthorhombicPt. Group: 2/m 2/m 2/mHabit: acicular, radiating crystals, globular SG: 2.34; H: 3.5-4 L: vitreous-waxy; Str: whiteCol: shades of green/greenish yellowClev: prefect [110], good [101]Optics: Biaxial +nα= 1.530; nβ= 1.682; nγ= 1.686Name derivation: Named after British mineralogist William Wavell (? To 1829)Phosphate MineralsWavellite(Al3(PO4)2(OH)3·2H2O)Occurrence: secondary mineral in aluminum-poor metamorphic rocks (e.g., Arkansas)Associated Mins: basic aluminum phosphatesCan be confused with: nothing I can think ofUses: nothingPhosphate MineralsPyromorphite (Pb5(PO4)3Cl)Crystal: HexagonalPt. Group: 6/mHabit: globular to slender prismatic crystalsSG: 6.85; H: 3.5-4L: vitreous to resinous; Str: whiteCol: green, yellow to brownClev: imperfectOptics: unaxial -ne= 2.049; nw= 2.059Name derivation: Greek for “fire” (pyr) and “form” (morfe)Phosphate MineralsPyromorphite (Pb5(PO4)3Cl)Occurrence: secondary minerals product in oxidized zones of leadAssociated Mins: limonite, cerussite, malachiteCan be confused with:mimetite, malachite (if you’re having a bad day)Uses: bookenditePhosphate MineralsVanadinite (Pb5(VO4)3Cl )Crystal: HexagonalPt. Group: 6/mHabit: hexagonal to prismatic crystalsSG: 6.94; H: 3.5-4L: vitreous;
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