Scottyite, the natural analog of synthetic BaCu2Si2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa
-
Hexiong Yang
,
Robert T. Downs
Abstract
A new mineral species, scottyite, ideally BaCu2Si2O7, has been found in the Wessels mine, Kalahari Manganese Fields, Northern Cape Province, South Africa. The mineral appears to have formed as a result of a hydrothermal event and is associated with wesselsite, pectolite, richterite, sugilite, and lavinskyite. Scottyite forms blocky grains with striations parallel to the c axis. Crystals are found up to 0.4 × 0.3 × 0.3 mm. No twinning is observed. The mineral is dark-blue in transmitted and under incident lights, transparent with pale blue streak and vitreous luster. It is brittle and has a Mohs hardness of 4-5; cleavage is perfect on {100} and {010} and no parting was observed. The calculated density is 4.654 g/cm3. Optically, scottyite is biaxial (-), with α = 1.750(1), β = 1.761(1), and γ = 1.765(1), 2Vmeas = 66(2)°. It is insoluble in water, acetone, or hydrochloric acid. An electron microprobe analysis produced an average composition (wt%) (8 points) of CuO 36.98(31), BaO 35.12(16), SiO2 27.01(61), SrO 0.28(5), and Na2O 0.06(2), and total = 99.45(65), yielding an empirical formula (based on 7 O apfu) Ba1.00Sr0.01Na0.01Cu2.04Si1.97O7.
Scottyite is the natural analog of synthetic BaCu2(Si,Ge)2O7, which exhibits novel one-dimensional quantum spin-1/2 antiferromagnetic properties with tunable super-exchange interactions. It is orthorhombic, with space group Pnma and unit-cell parameters a = 6.8556(2), b = 13.1725(2), c = 6.8901(1) Å, and V = 622.21(6) Å3. The structure of scottyite is characterized by flattened CuO4 tetrahedra sharing corners with one another to form chains parallel to the c axis. These chains are interlinked by Si2O7 tetrahedral dimers and Ba2+. The Ba2+ cations are bonded to seven O atoms in an irregular coordination. The average Si-O, Cu-O, and Ba-O bond lengths are 1.630, 1.941, and 2.825 Å, respectively. Scottyite is topologically related to a group of compounds with the general formula BaM2+ 2 Si2O7, where M = Be (barylite and clinobarylite), Fe (andrémeyerite), Mg, Mn, Co, and Zn.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Pressure-induced structural transformations in the low-cristobalite form of AlPO4
- Hydrokenomicrolite, (□,H2O)2Ta2(O,OH)6(H2O), a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil
- Fluor-elbaite, Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3F, a new mineral species of the tourmaline supergroup
- Microtexture development during rapid cooling in three rhyolitic lava flows
- Microbial and inorganic control on the composition of clay from volcanic glass alteration experiments
- High-pressure experiments on phase transition boundaries between corundum, Rh2O3(II)- and CaIrO3-type structures in Al2O3
- Electronic structure effects in the vectorial bond-valence model
- Geometric analysis of radiation damage connectivity in zircon, and its implications for helium diffusion
- Superstructure, crystal chemistry, and cation distribution in filipstadite, a Sb5+-bearing, spinel-related mineral
- A high-temperature Brillouin scattering study on four compositions of haplogranitic glasses and melts: High-frequency elastic behavior through the glass transition
- Hydrogen isotope fractionation between coexisting hydrous melt and silicate-saturated aqueous fluid: An experimental study in situ at high pressure and temperature
- Eclogitic clasts with omphacite and pyrope-rich garnet in the NWA 801 CR2 chondrite
- Hydration properties of synthetic high-charge micas saturated with different cations: An experimental approach
- Quantitative analyses of powdered multi-minerallic carbonate aggregates using a portable Raman spectrometer
- Periodic ab initio bulk investigation of hydroxylapatite and type A carbonated apatite with both pseudopotential and all-electron basis sets for calcium atoms
- Coexisting pseudobrookite, ilmenite, and titanomagnetite in hornblende andesite of the Coleman Pinnacle flow, Mount Baker, Washington: Evidence for a highly oxidized arc magma
- Geochemistry of pyrochlore minerals from the Motzfeldt Center, South Greenland: The mineralogy of a syenite-hosted Ta, Nb deposit
- Phosphovanadylite-Ca, Ca[V4 4+P2O8(OH)8]·12H2O, the Ca analogue of phosphovanadylite-Ba
- The relationship between REE-Y-Nb-Th minerals and the evolution of an A-type granite, Wentworth Pluton, Nova Scotia
- Prewittite, KPb1.5Cu6Zn(SeO3)2O2Cl10, a new mineral from Tolbachik fumaroles, Kamchatka peninsula, Russia: Description and crystal structure
- Lucabindiite, (K,NH4)As4O6(Cl,Br), a new fumarole mineral from the “La Fossa” crater at Vulcano, Aeolian Islands, Italy
- Scottyite, the natural analog of synthetic BaCu2Si2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa
- Oxy-schorl, Na(Fe2 2+Al)Al6Si6O18(BO3)3(OH)3O, a new mineral from Zlatá Idka, Slovak Republic and Přibyslavice, Czech Republic
- Crystal chemistry and hydrogen bonding of rustumite Ca10(Si2O7)2(SiO4)(OH)2Cl2 with variable OH, Cl, F
- Oxy-vanadium-dravite, NaV3(V4Mg2)(Si6O18)(BO3)3(OH)3O: Crystal structure and redefinition of the “vanadium-dravite” tourmaline
- Lead-tellurium oxysalts from Otto Mountain near Baker, California: VIII. Fuettererite, Pb3Cu2+ 6 Te6+O6(OH)7Cl5, a new mineral with double spangolite-type sheets
- Lead-tellurium oxysalts from Otto Mountain near Baker, California: IX. Agaite, Pb3Cu2+Te6+O5(OH)2(CO3), a new mineral with CuO5-TeO6 polyhedral sheets
- Letter: Actinides in Geology, Energy, and the Environment. Evidence for nanocrystals of vorlanite, a rare uranate mineral, in the Nopal I low-temperature uranium deposit (Sierra Peña Blanca, Mexico)
Articles in the same Issue
- Pressure-induced structural transformations in the low-cristobalite form of AlPO4
- Hydrokenomicrolite, (□,H2O)2Ta2(O,OH)6(H2O), a new microlite-group mineral from Volta Grande pegmatite, Nazareno, Minas Gerais, Brazil
- Fluor-elbaite, Na(Li1.5Al1.5)Al6(Si6O18)(BO3)3(OH)3F, a new mineral species of the tourmaline supergroup
- Microtexture development during rapid cooling in three rhyolitic lava flows
- Microbial and inorganic control on the composition of clay from volcanic glass alteration experiments
- High-pressure experiments on phase transition boundaries between corundum, Rh2O3(II)- and CaIrO3-type structures in Al2O3
- Electronic structure effects in the vectorial bond-valence model
- Geometric analysis of radiation damage connectivity in zircon, and its implications for helium diffusion
- Superstructure, crystal chemistry, and cation distribution in filipstadite, a Sb5+-bearing, spinel-related mineral
- A high-temperature Brillouin scattering study on four compositions of haplogranitic glasses and melts: High-frequency elastic behavior through the glass transition
- Hydrogen isotope fractionation between coexisting hydrous melt and silicate-saturated aqueous fluid: An experimental study in situ at high pressure and temperature
- Eclogitic clasts with omphacite and pyrope-rich garnet in the NWA 801 CR2 chondrite
- Hydration properties of synthetic high-charge micas saturated with different cations: An experimental approach
- Quantitative analyses of powdered multi-minerallic carbonate aggregates using a portable Raman spectrometer
- Periodic ab initio bulk investigation of hydroxylapatite and type A carbonated apatite with both pseudopotential and all-electron basis sets for calcium atoms
- Coexisting pseudobrookite, ilmenite, and titanomagnetite in hornblende andesite of the Coleman Pinnacle flow, Mount Baker, Washington: Evidence for a highly oxidized arc magma
- Geochemistry of pyrochlore minerals from the Motzfeldt Center, South Greenland: The mineralogy of a syenite-hosted Ta, Nb deposit
- Phosphovanadylite-Ca, Ca[V4 4+P2O8(OH)8]·12H2O, the Ca analogue of phosphovanadylite-Ba
- The relationship between REE-Y-Nb-Th minerals and the evolution of an A-type granite, Wentworth Pluton, Nova Scotia
- Prewittite, KPb1.5Cu6Zn(SeO3)2O2Cl10, a new mineral from Tolbachik fumaroles, Kamchatka peninsula, Russia: Description and crystal structure
- Lucabindiite, (K,NH4)As4O6(Cl,Br), a new fumarole mineral from the “La Fossa” crater at Vulcano, Aeolian Islands, Italy
- Scottyite, the natural analog of synthetic BaCu2Si2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa
- Oxy-schorl, Na(Fe2 2+Al)Al6Si6O18(BO3)3(OH)3O, a new mineral from Zlatá Idka, Slovak Republic and Přibyslavice, Czech Republic
- Crystal chemistry and hydrogen bonding of rustumite Ca10(Si2O7)2(SiO4)(OH)2Cl2 with variable OH, Cl, F
- Oxy-vanadium-dravite, NaV3(V4Mg2)(Si6O18)(BO3)3(OH)3O: Crystal structure and redefinition of the “vanadium-dravite” tourmaline
- Lead-tellurium oxysalts from Otto Mountain near Baker, California: VIII. Fuettererite, Pb3Cu2+ 6 Te6+O6(OH)7Cl5, a new mineral with double spangolite-type sheets
- Lead-tellurium oxysalts from Otto Mountain near Baker, California: IX. Agaite, Pb3Cu2+Te6+O5(OH)2(CO3), a new mineral with CuO5-TeO6 polyhedral sheets
- Letter: Actinides in Geology, Energy, and the Environment. Evidence for nanocrystals of vorlanite, a rare uranate mineral, in the Nopal I low-temperature uranium deposit (Sierra Peña Blanca, Mexico)
