Chapter 23 Sulfates, phosphates and related minerals Apatite as a biogenic mineral

Introduction Fundamental building block: Fundamental building block: PO 4 3- (phosphates) or SO 4 2- (sulfates) tetrahedron PO 4 3- (phosphates) or SO 4 2- (sulfates) tetrahedron Several phosphate structures identical to silicate structures Several phosphate structures identical to silicate structures Berlinite (AlPO 4 ) – quartz (SiO 2 ) Berlinite (AlPO 4 ) – quartz (SiO 2 ) Triphyline (LiFePO 4 ) – olivine (Mg 2 SiO 4 ) Triphyline (LiFePO 4 ) – olivine (Mg 2 SiO 4 ) Xenotime (YPO 4 ) – zircon (ZrSiO 4 ) Xenotime (YPO 4 ) – zircon (ZrSiO 4 ) Mostly isolated polyhedra unlike most silicates were tetrahedrons are polimerized into sheets, chains, frameworks Mostly isolated polyhedra unlike most silicates were tetrahedrons are polimerized into sheets, chains, frameworks Phosphates are related to arsenates (AsO 4 3- ), vanadates (VO 4 3- ) and tungstates (WO 4 2- ) Phosphates are related to arsenates (AsO 4 3- ), vanadates (VO 4 3- ) and tungstates (WO 4 2- ) Economic interest: apatite, gypsum, scheelite Economic interest: apatite, gypsum, scheelite

Classification Class VIII: Phosphates, arsenates and vanadates Class VIII: Phosphates, arsenates and vanadates Class IX: Sulfates Class IX: Sulfates Class X: Tungstates and Molybdates Class X: Tungstates and Molybdates Class XI: Chromates Class XI: Chromates Class XII: Nitrates Class XII: Nitrates

Class VIII: Phosphate, arsenates and vanadates (Table 23.1) 250 minerals; very small amount of earth’s crust 250 minerals; very small amount of earth’s crust Apatite very important Apatite very important Be-Al-Mg association Be-Al-Mg association Variscite-Strengite Group Variscite-Strengite Group Lazulite Group Lazulite Group Fe-Mn-Na association Fe-Mn-Na association Pharmacosiderite Group Pharmacosiderite Group Triphyline Group Triphyline Group Na-Ca-REE association Na-Ca-REE association Apatite Group Apatite Group Monazite Group Monazite Group Zn-Cu-Pb association Zn-Cu-Pb association Tarbuttite-Adamite Group Tarbuttite-Adamite Group Pyromorphite Group Pyromorphite Group Descloizite Group Descloizite Group Tobernite-Zeunerite Group Tobernite-Zeunerite Group Carnotite Group Carnotite Group

Na-Ca-REE association Apatite Ca 5 (PO 4 ) 3 (F,Cl,OH) Single phosphate Single phosphate Hexagonal Hexagonal Fluorapatite (F), chlorapatite (Cl), hydroxylapatite (OH), carbonylapatite (CO 3 ) Fluorapatite (F), chlorapatite (Cl), hydroxylapatite (OH), carbonylapatite (CO 3 ) Can contain Sr or Ce Can contain Sr or Ce Well-developed crystals: prismatic, ending with pinacoidal faces Well-developed crystals: prismatic, ending with pinacoidal faces Occurrence: widespread; usually as small grains – largest grains in granite, pegmatites and marbles; can make up 80 wt% of alkaline rocks Occurrence: widespread; usually as small grains – largest grains in granite, pegmatites and marbles; can make up 80 wt% of alkaline rocks Used as fertilizer Used as fertilizer

Na-Ca-REE association Monazite CePO 4 Contains other REE, as well as Th and U Contains other REE, as well as Th and U Found in granite pegmatites: resembles garnet, but have cleavage and lower hardness Found in granite pegmatites: resembles garnet, but have cleavage and lower hardness As minute inclusions in gneisses: usually in cordierite producing pleochroic halos As minute inclusions in gneisses: usually in cordierite producing pleochroic halos Mined from river and coastal sands as REE, Th and U source Mined from river and coastal sands as REE, Th and U source

Zn-Cu-Pb-(U) Association Uranium micas Torbernite (Cu 2 (UO 2 ) 2 (PO 4 ) 2.10H 2 O Torbernite (Cu 2 (UO 2 ) 2 (PO 4 ) 2.10H 2 O Autunite (Ca(UO 2 ) 2 (PO 4 ) 2.10H 2 O Autunite (Ca(UO 2 ) 2 (PO 4 ) 2.10H 2 O Carnotite (K 2 (UO 2 ) 2 (VO 4 ) 2.3H 2 O Carnotite (K 2 (UO 2 ) 2 (VO 4 ) 2.3H 2 O Occur as powdery aggregates or platy crystals Occur as powdery aggregates or platy crystals High radioactivity High radioactivity Carnotite: ore for vanadium and uranium Carnotite: ore for vanadium and uranium

Turquoise CuAl 6 (PO 4 ) 4 (OH) 8.4H 2 O Cryptocrystalline Cryptocrystalline Blue – blue-green aggregates Blue – blue-green aggregates Secondary mineral in veins of altered volcanic rocks Secondary mineral in veins of altered volcanic rocks Rare gemstone Rare gemstone

Class IX: Sulfates (Table 23.2) Salt of sulfuric acid: H 2 SO 4 Salt of sulfuric acid: H 2 SO 4 Important associations: Important associations: Na(K)-Ca-Ba association Na(K)-Ca-Ba association Anhydrite Anhydrite Gypsum Gypsum Celestite Celestite Barite Barite Cu-Pb-Zn association Cu-Pb-Zn association Chalcanthite Chalcanthite Anglesite Anglesite

Anhydrite CaSO 4 Evaporite mineral Evaporite mineral Hydrothermal sulfide ore deposits Hydrothermal sulfide ore deposits Some metamorphic rocks Some metamorphic rocks Does not react with HCl Does not react with HCl Raw material for cement production Raw material for cement production

Gypsum CaSO 4.2H 2 O Evaporite mineral Evaporite mineral Forms alternating layers with anhydrite and halite precipitating from solutions Forms alternating layers with anhydrite and halite precipitating from solutions Hydrothermal mineral from meteoric water Hydrothermal mineral from meteoric water On surface of clay or sand – flower- like morphology (desert rose) On surface of clay or sand – flower- like morphology (desert rose) Mostly flattened and prismatic crystals; distinctive swallowtail twins very common Mostly flattened and prismatic crystals; distinctive swallowtail twins very common Use: cement and plaster in construction industry Use: cement and plaster in construction industry

Celestite and Barite (SrSO 4 and BaSO 4 ) Limited solid solution Limited solid solution Found in druses and granular aggregates Found in druses and granular aggregates Forms in Forms in Barite: Hydrothermal deposits Barite: Hydrothermal deposits Celestite: Secretions in sedimentary rocks Celestite: Secretions in sedimentary rocks Uses Uses Barite: paint, in chemical, rubber, paper industries, drilling additive Barite: paint, in chemical, rubber, paper industries, drilling additive Celestite: sugar manufacturing, pyrotechnology, pharmaceuticals Celestite: sugar manufacturing, pyrotechnology, pharmaceuticals

Anglesite PbSO 4 Massive granular and colloform aggregates Massive granular and colloform aggregates Prismatic-tabular crystals Prismatic-tabular crystals Product of galena oxidation Product of galena oxidation High S.G. High S.G. So does barite and cerussite So does barite and cerussite Anglesite and cerussite often associated with galena, barite not Anglesite and cerussite often associated with galena, barite not Cerussite, PbCO 3, effervesce with HCl Cerussite, PbCO 3, effervesce with HCl

Alunite KAl 3 (SO 4 ) 2 (OH) 6 Hydrothermal alteration of felsic rocks Hydrothermal alteration of felsic rocks Felsic volcanic rocks interact with sulfuric hydrothermal solutions Felsic volcanic rocks interact with sulfuric hydrothermal solutions 3KAlSi 3 O 8 + 2SO H +  3KAlSi 3 O 8 + 2SO H +  K-feldspar K-feldspar KAl 3 (SO 4 ) 2 (OH) 6 + 9SiO 2 + 2K + + 4H 2 O Alunite Aluminum ore and source of K Aluminum ore and source of K

Class X: Tungstates Closely related to sulfates Closely related to sulfates WO 4 2- tetrahedra instead of SO 4 2- WO 4 2- tetrahedra instead of SO 4 2- Wolframite Wolframite Isomorphic series: FeWO 4 -MnWO 4 Isomorphic series: FeWO 4 -MnWO 4 Monoclinic Monoclinic Mistaken for sphalerite: Mistaken for sphalerite: Sphalerite has several cleavages, isometric crystals, lower density Sphalerite has several cleavages, isometric crystals, lower density Forms in quartz veins and placers Forms in quartz veins and placers Tungsten ore Tungsten ore Scheelite Scheelite CaWO 4 CaWO 4 Forms in quartz veins and in skarns Forms in quartz veins and in skarns Can be mistaken for quartz or calcite Can be mistaken for quartz or calcite Blue and white fluorescence diagnostic; Blue and white fluorescence diagnostic; much softer than quartz; heavier than calcite Major tungsten ore Major tungsten ore

Biogenic processes Biogenic minerals forms in surface Biogenic minerals forms in surface environments by: Transformations of primary organic aggregates or Transformations of primary organic aggregates or Biochemical processes Biochemical processes Originate from living organisms or with their assistance Originate from living organisms or with their assistance Not strictly minerals, but is the same substance as produced inorganically in rocks Not strictly minerals, but is the same substance as produced inorganically in rocks Crystallize within organism and are surrounded with organic material Crystallize within organism and are surrounded with organic material Bones & teeth: platy crystals closely related to carbonate-hydroxylapatite suspended in protein – comprise up to 70% of dried bones Bones & teeth: platy crystals closely related to carbonate-hydroxylapatite suspended in protein – comprise up to 70% of dried bones Various minerals in: mollusk shells, corals, trilobites, algae, egg shells Various minerals in: mollusk shells, corals, trilobites, algae, egg shells Aragonite in mother-of-pearl Aragonite in mother-of-pearl Kidney stones, gall stones Kidney stones, gall stones 80 different minerals in fossil and recent animals and plants 80 different minerals in fossil and recent animals and plants Calcite in eye-lenses in extinct trilobites and on body of eyeless brittlestar (starfish) Calcite in eye-lenses in extinct trilobites and on body of eyeless brittlestar (starfish) Magnetite: biomineralogical navigation system for pigeons, bacteria Magnetite: biomineralogical navigation system for pigeons, bacteria Bacteria NB in formation of some ore deposits and weathering processes Bacteria NB in formation of some ore deposits and weathering processes Table 23.3 Table 23.3