Poldervaartite Mineral Data

Poldervaartite Mineral Data +

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General Poldervaartite Information

Chemical Formula:

(Ca,Mn++)2SiO3(OH)2

Composition:

Molecular Weight = 197.68 gm

Calcium 30.41 % Ca 42.55 % CaO

Manganese 13.90 % Mn 17.94 % MnO

Silicon 14.21 % Si 30.39 % SiO₂

Hydrogen 1.02 % H 9.11 % H₂O

Oxygen 40.47 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_1.5Mn²⁺_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

IMA1992-012

PDF 46-1435

Poldervaartite Image

Images:

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

Images:

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

Poldervaartite Crystallography

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

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 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

Physical Properties of Poldervaartite

Cleavage:

None

Color:

Colorless, Milky white.

Density:

2.91

Diaphaniety:

Transparent to Translucent

Hardness:

5 - Apatite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Poldervaartite

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.

Calculated Properties of Poldervaartite

Electron Density:

r_electron=2.90 gm/cc
note: r_{Poldervaartite}=2.91 gm/cc.

Fermion Index

Fermion Index = 0.00724
Boson Index = 0.99276

Photoelectric:

PE_{Poldervaartite}= 7.75 barns/electron
U=PE_{Poldervaartite} x r_electron= 22.48 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Poldervaartite is Not Radioactive

Poldervaartite Classification

Dana Class:

78.1.8.1 (78)Unclassified silicates

(78.1)possible nesosilicates

(78.1.8)Dana Group

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

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cationes with coordinationnumber between [8] and [12]

VIII/B.22 - Thaumasite series

VIII/B.22-10 Hatrurite Ca3SiO5 R 3m 3m

VIII/B.22-25 Poldervaartite (Ca,Mn)2SiO3(OH)2 P bca 2/m 2/m 2/m

VIII/B.22-30 Afwillite Ca3Si2O4(OH)6 P 2₁ 2

VIII/B.22-40 Bultfonteinite Ca2SiO2(OH,F)4 P1 1

VIII/B.22-50 Spurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-60 Paraspurrite Ca5(SiO4)2(CO3) P 2₁/a 2/m

VIII/B.22-65 Ternesite! Ca5(SiO4)2SO4 P nma 2/m 2/m 2/m

VIII/B.22-70 Nagelschmidtite Ca7(SiO4)3(PO4)2 Unk Hex

VIII/B.22-75 Harrisonite! Ca(Fe,Mg)6(PO4)2(SiO4)2 R 3m 3 2/m

VIII/B.22-80 Fukalite Ca4Si2O6(CO3)(OH,F)2 Unk Ortho

VIII/B.22-90 Thaumasite Ca3Si(CO3)(SO4)(OH)6·12(H2O) P 6₃/m 6/m

VIII/B.22-100 Chelyabinskite* (Ca,Mg)3Si(OH)6(SO4,CO3)2·9(H2O) Unk Ortho

Other Poldervaartite Information

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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Poldervaartite

(Ca,Mn++)2SiO3(OH)2
Dana No: 78.1.8.1 Strunz No: VIII/B.22-25
Locality:

Notes: