Pararobertsite Mineral Data

General Pararobertsite Information

Chemical Formula:

Ca2Mn+++3(PO4)3O2•3(H2O)

Composition:

Molecular Weight = 615.93 gm

Calcium 13.01 % Ca 18.21 % CaO

Manganese 26.76 % Mn 38.45 % Mn₂O₃

Phosphorus 15.09 % P 34.57 % P₂O₅

Hydrogen 0.98 % H 8.77 % H₂O

Oxygen 44.16 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂Mn³⁺₃(PO₄)₃O₂•3(H₂O)

Environment:

Rare secondary mineral in a complex zoned granite pegmatite.

IMA Status:

Approved IMA 1989

Locality:

Tip Top mine, 8.5 km southwest of Custer, Custer Co., South Dakota, USA. Link to MinDat.org Location Data.

Name Origin:

From the Greek para, for near, and its relation to robertsite.

Name Pronunciation:

Pararobertsite + Pronunciation

Synonym:

ICSD 89712

PDF 45-1440

Pararobertsite Image

Images:

Pararobertsite

Comments: SEM image of a group of pararobertsite crystals illustraing the typical habit. (CanMin, v27:451).
Location: Tip Top pegmatite, Custer County, South Dakota, USA. Scale: Scale Bar 100 µm.
© Canadian Mineralogist

Pararobertsite Crystallography

Axial Ratios:

a:b:c =0.6656:1:0.8362

Cell Dimensions:

a = 8.825, b = 13.258, c = 11.087, Z = 4; beta = 101.19° V = 1,272.54 Den(Calc)= 3.21

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/c

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

By Intensity(I/I_o): 8.69(1), 2.884(0.6), 5.66(0.6),

Crystal Structure:

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Kampf A R , American Mineralogist , 85 (2000) p.1302-1306, The crystal structure of pararobertsite and its relationship to mitridatite

Physical Properties of Pararobertsite

Cleavage:

{100} Perfect

Color:

Bronze, Yellow, Dark red.

Density:

3.22

Diaphaneity:

Transparent

Hardness:

2 - Gypsum

Luster:

Vitreous (Glassy)

Streak:

brown red

Optical Properties of Pararobertsite

Gladstone-Dale:

CI meas= -0.018 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.021 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2523,KPDmeas= 0.2516,KC= 0.2471
Ncalc = 1.79 - 1.8

Optical Data:

Biaxial (-), a=1.79, b=1.81, g=1.83, bire=0.0400, 2V(Calc)=88, 2V(Meas)=84.

Calculated Properties of Pararobertsite

Electron Density:

Bulk Density (Electron Density)=3.16 gm/cc
note: Specific Gravity of Pararobertsite =3.22 gm/cc.

Fermion Index:

Fermion Index = 0.0003891242
Boson Index = 0.9996108758

Photoelectric:

PE_{Pararobertsite}= 9.13 barns/electron
U=PE_{Pararobertsite} x rElectron Density= 28.83 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Pararobertsite is Not Radioactive

Pararobertsite Classification

Dana Class:

42.08.05.02 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen

(42.08)where (AB)7 (XO4)4 Zq · x(H2O)

(42.08.05)Kolfanite Group

42.08.05.01 Kolfanite Ca2Fe3O2(AsO4)3•2(H2O) A2/a 2/m

42.08.05.02 Pararobertsite Ca2Mn3(PO4)3O2•3(H2O) P 2₁/c 2/m

42.08.05.03 Sailaufite! Ca2Mn3O2(AsO4)2(CO3)•3(H2O) Cm m

Strunz Class:

08.DH.30 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DH -With large and medium-sized cations, (OH, etc.):RO4 < 1:1

08.DH.30 Arseniosiderite Ca2Fe3(AsO4)3O2•3(H2O) A2/a 2/m

08.DH.30 Pararobertsite Ca2Mn3(PO4)3O2•3(H2O) P 2₁/c 2/m

08.DH.30 Kolfanite Ca2Fe3O2(AsO4)3•2(H2O) A2/a 2/m

08.DH.30 Lunokite (Mn,Ca)(Mg,Fe,Mn)Al(PO4)2(OH)•4(H2O) P bca 2/m 2/m 2/m

08.DH.30 Robertsite Ca6Mn9(PO4)9O6(H2O)6•3(H2O) A2/a 2/m

08.DH.30 Mitridatite Ca2Fe3(PO4)3O2•3(H2O) A2/a 2/m

08.DH.30 Sailaufite! Ca2Mn3O2(AsO4)2(CO3)•3(H2O) Cm m

Other Pararobertsite Information

References:

NAME( AntBidBlaNic4) PHYS. PROP.(Am.Min.,Vol.75,p1211,1990) OPTIC PROP.(Am.Min.,Vol.75,p1211,1990)

See Also:

Links to other databases for Pararobertsite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - MinDAT
10 - Mineralienatlas (Deutsch)
11 - Online Mineral Museum
12 - QUT Mineral Atlas
13 - Ruff.Info

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Ask about Pararobertsite here :
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Print or Cut-and-Paste your Pararobertsite Specimen Label here :

Pararobertsite

Ca2Mn+++3(PO4)3O2•3(H2O)
Dana No: 42.08.05.02 Strunz No: 08.DH.30
Locality:

Notes: