General Poldervaartite Information
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Chemical Formula: |
(Ca,Mn++)2SiO3(OH)2 |
Composition: |
Molecular Weight = 197.68 gm |
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Calcium 30.41 % Ca 42.55 % CaO |
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Manganese 13.90 % Mn 17.94 % MnO |
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Silicon 14.21 % Si 30.39 % SiO2 |
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Hydrogen 1.02 % H 9.11 % H2O |
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Oxygen 40.47 % O |
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______ ______ |
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100.00 % 100.00 % = TOTAL OXIDE |
Empirical Formula: |
Ca1.5Mn2+0.5SiO3(OH)2 |
Environment: |
In a pocket in massive manganese ores in a bedded manganese ore deposit. |
IMA Status: |
Approved IMA 1993 |
Locality: |
Wessels mine, near Kuruman, Cape Province, South Africa. Link to MinDat.org Location Data. |
Name Origin: |
Named for Arie Poldervaart (1918-1964), Professor of Petrology, Columbia University, New York City, New York, USA. |
Synonym: |
ICSD 74005 |
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IMA1992-012 |
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PDF 46-1435 |
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Poldervaartite Image |
Images:
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Poldervaartite
Comments: Moderate reddish tint to yellowish poldervaartite crystalline druze on matrix.
Location: N'chwaning II mine, section 5 south, stope 46-47 roof, Kuruman, Kalahari desert, South Africa.
Scale: 6 x 3.5 x 4 cm.
© Fabre Minerals |
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Images:
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Poldervaartite Bultfonteinite
Comments: Bow-tie clusters of white, acicular bultfonteinite and blocky, beige-colored poldervaartite on matrix.
Location: N'Chwaning mine, South Africa.
Scale: picture size 4 cm.
© John Veevaert |
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Poldervaartite Crystallography
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Axial Ratios: |
a:b:c =1.0283:1:1.1527 |
Cell Dimensions: |
a = 9.398, b = 9.139, c = 10.535, Z = 8; V = 904.83 Den(Calc)= 2.90 |
Crystal System: |
Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: P bca |
X Ray Diffraction: |
By Intensity(I/Io): 3.231(1), 4.18(0.45), 2.846(0.42), |
Crystal Structure:
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Dai Y S , Harlow G E , McGhie A R , American Mineralogist , 78 (1993) p.1082-1087, Poldervaartite, Ca(Ca0.5Mn0.5)(SiO3OH)(OH), a new acid nesosilicate from the, Kalahari manganese field, South Africa: Crystal structure and description
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Physical Properties of Poldervaartite
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Cleavage: |
None |
Color: |
Colorless, Milky white. |
Density: |
2.91 |
Diaphaniety: |
Transparent to Translucent |
Hardness: |
5 - Apatite |
Luster: |
Vitreous (Glassy) |
Streak: |
white |
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Optical Properties of Poldervaartite
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Gladstone-Dale: |
CI meas= -0.01 (Superior) - where the CI = (1-KPDmeas/KC) CI calc= -0.013 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2218,KPDmeas= 0.2211,KC= 0.2189 |
Optical Data: |
Biaxial (+), a=1.634, b=1.64, g=1.656, bire=0.0220, 2V(Calc)=64, 2V(Meas)=63-65. |
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Calculated Properties of Poldervaartite
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Electron Density: |
relectron=2.90 gm/cc note: rPoldervaartite =2.91 gm/cc. |
Fermion Index |
Fermion Index = 0.00724 Boson Index = 0.99276 |
Photoelectric: |
PEPoldervaartite = 7.75 barns/electron U=PEPoldervaartite x relectron= 22.48 barns/cc. |
Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Poldervaartite is Not Radioactive |
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Poldervaartite Classification
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Dana Class: |
78.1.8.1 (78)Unclassified silicates |
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(78.1)possible nesosilicates |
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(78.1.8)Dana Group |
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78.1.8.1 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m |
Strunz Class: |
VIII/B.22-25 VIII - Silicates |
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VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cationes with coordinationnumber between [8] and [12] |
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VIII/B.22 - Thaumasite series |
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VIII/B.22-10 Hatrurite Ca3SiO5 R 3m 3m |
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VIII/B.22-25 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m |
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VIII/B.22-30 Afwillite Ca3Si2O4(OH)6 P 21 2 |
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VIII/B.22-40 Bultfonteinite Ca2SiO2(OH,F)4 P1 1 |
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VIII/B.22-50 Spurrite Ca5(SiO4)2(CO3) P 21/a 2/m |
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VIII/B.22-60 Paraspurrite Ca5(SiO4)2(CO3) P 21/a 2/m |
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VIII/B.22-65 Ternesite! Ca5(SiO4)2SO4 P nma 2/m 2/m 2/m |
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VIII/B.22-70 Nagelschmidtite Ca7(SiO4)3(PO4)2 Unk Hex |
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VIII/B.22-75 Harrisonite! Ca(Fe,Mg)6(PO4)2(SiO4)2 R 3m 3 2/m |
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VIII/B.22-80 Fukalite Ca4Si2O6(CO3)(OH,F)2 Unk Ortho |
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VIII/B.22-90 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 63/m 6/m |
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VIII/B.22-100 Chelyabinskite* (Ca,Mg)3Si(OH)6(SO4,CO3)2·9(H2O) Unk Ortho |
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Other Poldervaartite Information
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References: |
NAME( AntBidBlaNic2) PHYS. PROP.(Am.Min.,Vol.78,p1082-1087,1993) OPTIC PROP.(Am.Min.,Vol.78,p1082-1087,1993) |
See Also: |
Links to other databases for Poldervaartite :
1 -Am. Min. Crystal Structure Database
2 -Athena
3 - EUROmin Project
4 -Google Images
5 -Google Scholar
6 -Handbook of Mineralogy (MinSocAm)
7 -Handbook of Mineralogy (UofA)
8 -MinDAT
9 -MinMax(Deutsch)
10 -MinMax(English)
11 -Mineralienatlas (Deutsch)
12 -QUT Mineral Atlas
13 - WWW-MINCRYST
14 -École des Mines de Paris
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Print or Cut-and-Paste your Poldervaartite Specimen Label here :
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Poldervaartite
(Ca,Mn++)2SiO3(OH)2
Dana No: 78.1.8.1 Strunz No: VIII/B.22-25
Locality:
Notes:
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