Major Clay MineralsSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Clay building blocksSlide 10Calcite vs. DolomiteCalcite GroupDolomite GroupAragonite GroupCarbonate MineralsSlide 16Sulfate MineralsGypsumSlide 19Halide MineralsHalite StructureFlourite structureSulfate Minerals IIBarite, Celestite, AnglesiteJust silica…Opal - GemstoneAgatesOxides - OxyhydroxidesSlide 29Mn oxides - oxyhydroxidesMn Oxide minerals (not all…)Iron OxidesFerrihydriteGoethiteSlide 35Slide 36Banded Iron Formations (BIFs)Major Clay Minerals•Kaolinite – Al2Si2O5(OH)4•Illite – K1-1.5Al4(Si,Al)8O20(OH)4•Smectites:–Montmorillonite – (Ca, Na)0.2-0.4(Al,Mg,Fe)2(Si,Al)4O10(OH)2*nH2O–Vermicullite - (Ca, Mg)0.3-0.4(Al,Mg,Fe)3(Si,Al)4O10(OH)2*nH2O–Swelling clays – can take up extra water in their interlayers and are the major components of bentonite (NOT a mineral, but a mix of different clay minerals)SiO4 tetrahedra polymerized into 2-D sheets: [Si2O5]Apical O’s are unpolymerized and are bonded to other constituentsPhyllosilicatesTetrahedral layers are bonded to octahedral layers (OH) pairs are located in center of T rings where no apical OPhyllosilicatesOctahedral layers can be understood by analogy with hydroxidesPhyllosilicatesBrucite: Mg(OH)Brucite: Mg(OH)22Layers of octahedral Mg in Layers of octahedral Mg in coordination with (OH)coordination with (OH)Large spacing along Large spacing along cc due due to weak van der waals to weak van der waals bondsbondsccPhyllosilicatesGibbsite: Al(OH)Gibbsite: Al(OH)33Layers of octahedral Al in coordination with (OH)Layers of octahedral Al in coordination with (OH)AlAl3+3+ means that means that only 2/3 of the VI sites may be occupiedonly 2/3 of the VI sites may be occupied for charge-balance reasons for charge-balance reasonsBrucite-type layers may be called Brucite-type layers may be called trioctahedraltrioctahedral and gibbsite-type and gibbsite-type dioctahedraldioctahedralaa11aa22PhyllosilicatesKaolinite:Kaolinite: Al Al22 [Si [Si22OO55] (OH)] (OH)44T-layers and T-layers and didiocathedral (Alocathedral (Al3+3+) layers ) layers (OH) at center of T-rings and fill base of VI layer (OH) at center of T-rings and fill base of VI layer Yellow = (OH)Yellow = (OH)T T O O -- T T O O -- T T OOvdwvdwvdwvdwweak van der Waals bonds between T-O groups weak van der Waals bonds between T-O groupsPhyllosilicatesSerpentine:Serpentine: Mg Mg33 [Si [Si22OO55] (OH)] (OH)44T-layers and T-layers and tritriocathedral (Mgocathedral (Mg2+2+) layers ) layers (OH) at center of T-rings and fill base of VI layer (OH) at center of T-rings and fill base of VI layer Yellow = (OH)Yellow = (OH)T T O O -- T T O O -- T T OOvdwvdwvdwvdwweak van der Waals bonds between T-O groups weak van der Waals bonds between T-O groupsClay building blocks•Kaolinite micelles attached with H bonds – many H bonds aggregately strong, do not expend or swell1:1 ClayClay building blocks2:1 Clay•Slightly different way to deal with charge on the octahedral layer – put an opposite tetrahedral sheet on it…•Now, how can we put these building blocks together…Calcite vs. Dolomite•dolomite less reactive with HCl calcite has lower indices of refraction •calcite more commonly twinned •dolomite more commonly euhedral •calcite commonly colourless•dolomite may be cloudy or stained by iron oxide •Mg  spectroscopic techniques!•Different symmetry  cleavage same, but easily distinguished by XRDCalcite Group•Variety of minerals varying by cation•Ca  Calcite•Fe  Siderite•Mn  Rhodochrosite•Zn  Smithsonite•Mg  MagnesiteDolomite Group•Similar structure to calcite, but Ca ions are in alternating layers from Mg, Fe, Mn, Zn•Ca(Mg, Fe, Mn, Zn)(CO3)2–Ca  Dolomite–Fe  Ankerite–Mn  KutnahoriteAragonite Group•Polymorph of calcite, but the structure can incorporate some other, larger, metals more easily (Pb, Ba, Sr)–Ca  Aragonite–Pb  cerrusite–Sr  Strontianite–Ba  Witherite•Aragonite LESS stable than calcite, but common in biological material (shells….)Carbonate MineralsCalcite Group(hexagonal) Dolomite Group(hexagonal) AragoniteGroup(orthorhombic) mineral formula mineral formula mineral formulaCalcite CaCO3 Dolomite CaMg(CO3)2 Aragonite CaCO3 Magnesite MgCO3 Ankerite Ca(Mg,Fe)(CO3)2 Witherite BaCO3 Siderite, FeCO3 Kutnohorite CaMn(CO3)2 Strontianite SrCO3 Rhodochrosite MnCO3Carbonate MineralsMg FeCaCalcite, CaCO3DolomiteCaMg(CO3)2AnkeriteCaFe(CO3)2Siderite, FeCO3Magnesite, MgCO3Sulfate Minerals•More than 100 different minerals, separated into hydrous (with H2O) or anhydrous (without H2O) groups•Gypsum (CaSO4*2H2O) and anhydrite (CaSO4) are the most common of the sulfate minerals•Gypsum typically forms in evaporitic basins – a polymorph of anhydrite ( -CaSO4) forms when the gypsum is later dehydrated)Gypsum•Gypsum formation can demarcate ancient seas that dried up (such as the inland seas of the Michigan basin) or tell us about the history of current seas which have dried up before (such as the Mediterranean Sea)Halide Minerals•Minerals contianing halogen elements as dominant anion (Cl- or F- typically)•Halite (NaCl) and Sylvite (KCl) form in VERY concentrated evaporitic waters – they are extremely soluble in water, indicate more complete evaporation than does gypsum•Fluorite (CaF2) more typically occurs in veins associated with hydrothermal waters (F- in hydrothermal solutions is typically much higher – leached out of parent minerals such as biotites, pyroxenes, hornblendes or apatite)Halite Structure•NaCl  Na+ (gray) arranged in CCP with Cl- (red) at edges and center (in octahedral cavities)Flourite structure•CaF2  Ca2+ (gray) arranged in CCP, F- ions (red) inside ‘cage’Sulfate Minerals II•Barite (BaSO4), Celestite (SrSO4), and Anglesite (PbSO4) are also important in mining.•These minerals are DENSE  Barite =4.5, Anglesite = 6.3 (feldspars are ~2.5)Barite, Celestite, Anglesite•Metals bond with sulfate much more easily, and thus are generally more insoluble – they do not require formation in evaporitic basins•What do they indicate then?Ba, Pb, Sr – very low SO42-Lots of SO42-Not very much Ba, Sr, PbJust silica…•Chert – extremely fine grained quartz–Forms as nodules in limestone, recrystallization of siliceous fossils–Jasper – variety with hematite inclusions  red–Flint – variety containing organic matter  darker