Scottyite, the natural analog of synthetic BaCu2Si 2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa

Hexiong Yang, Robert T Downs, Stanley H. Evans, William W. Pinch

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A new mineral species, scottyite, ideally BaCu2Si 2O7, 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) Ba1.00Sr0.01Na0.01Cu 2.04Si1.97O7. 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 Si2O 7 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 BaM22+Si2O7, where M = Be (barylite and clinobarylite), Fe (andrémeyerite), Mg, Mn, Co, and Zn.

Original languageEnglish (US)
Pages (from-to)478-484
Number of pages7
JournalAmerican Mineralogist
Volume98
Issue number2-3
DOIs
StatePublished - Feb 2013

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Manganese mines
natural analog
Republic of South Africa
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Minerals
manganese
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hydrochloric acid
acetone
electron probe analysis
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cleavage
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Hydrochloric Acid

Keywords

  • BaCuSiO
  • Crystal structure
  • Raman spectra
  • Scottyite
  • X-ray diffraction

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

Cite this

Scottyite, the natural analog of synthetic BaCu2Si 2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa. / Yang, Hexiong; Downs, Robert T; Evans, Stanley H.; Pinch, William W.

In: American Mineralogist, Vol. 98, No. 2-3, 02.2013, p. 478-484.

Research output: Contribution to journalArticle

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title = "Scottyite, the natural analog of synthetic BaCu2Si 2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa",
abstract = "A new mineral species, scottyite, ideally BaCu2Si 2O7, 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) Ba1.00Sr0.01Na0.01Cu 2.04Si1.97O7. 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) {\AA}, and V = 622.21(6) {\AA}3. 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 Si2O 7 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 {\AA}, respectively. Scottyite is topologically related to a group of compounds with the general formula BaM22+Si2O7, where M = Be (barylite and clinobarylite), Fe (andr{\'e}meyerite), Mg, Mn, Co, and Zn.",
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author = "Hexiong Yang and Downs, {Robert T} and Evans, {Stanley H.} and Pinch, {William W.}",
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T1 - Scottyite, the natural analog of synthetic BaCu2Si 2O7, a new mineral from the Wessels mine, Kalahari Manganese Fields, South Africa

AU - Yang, Hexiong

AU - Downs, Robert T

AU - Evans, Stanley H.

AU - Pinch, William W.

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N2 - A new mineral species, scottyite, ideally BaCu2Si 2O7, 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) Ba1.00Sr0.01Na0.01Cu 2.04Si1.97O7. 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 Si2O 7 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 BaM22+Si2O7, where M = Be (barylite and clinobarylite), Fe (andrémeyerite), Mg, Mn, Co, and Zn.

AB - A new mineral species, scottyite, ideally BaCu2Si 2O7, 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) Ba1.00Sr0.01Na0.01Cu 2.04Si1.97O7. 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 Si2O 7 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 BaM22+Si2O7, where M = Be (barylite and clinobarylite), Fe (andrémeyerite), Mg, Mn, Co, and Zn.

KW - BaCuSiO

KW - Crystal structure

KW - Raman spectra

KW - Scottyite

KW - X-ray diffraction

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