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Robertsite Mineral Data

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General Robertsite Information

Help on Chemical  Formula: Chemical Formula: Ca6Mn+++9(PO4)9O6(H2O)6•3(H2O)
Help on Composition: Composition: Molecular Weight = 1,739.69 gm
   Calcium     13.82 %  Ca   19.34 % CaO
   Manganese   28.42 %  Mn   36.70 % MnO
   Phosphorus  16.02 %  P    36.72 % P2O5
   Hydrogen     0.35 %  H     3.11 % H2O
   Oxygen      41.39 %  O
              ______        ______ 
              100.00 %       95.86 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Ca6Mn2+9(PO4)9O6•3(H2O)
Help on IMA Status: IMA Status: Approved IMA 1974
Help on Locality: Locality: Tip Top mine, Custer County, South Dakota, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Willard Lincoln Roberts (1923-1987), mineralogist, South Dakota School of Mines.
Help on Name Pronunciation: Name Pronunciation: Robertsite + Pronunciation Say ROBERTSITE
 

Robertsite Image

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  Robertsite   Carbonate-hydroxylapatite   Apatite

Comments: Black crystals of Robertsite on pink carbonate-hydroxylapatite.
Location: Tip Top mine, Custer, Custer County, South Dakota, USA. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Robertsite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.8888:1:0.5785
Help on Cell Dimensions: Cell Dimensions: a = 17.36, b = 19.53, c = 11.3, Z = 4; beta = 96° V = 3,810.17 Den(Calc)= 3.03
Help on Crystal System: Crystal System: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: A2/a
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 8.63(1), 2.74(0.6), 5.61(0.5),
 

Physical Properties of Robertsite

Help on Cleavage: Cleavage: {100} Good
Help on Color: Color: Blood red, Brownish black, Dark red, Reddish brown, Black.
Help on Density: Density: 3.17
Help on Diaphaneity: Diaphaneity: Translucent to Opaque
Help on Habit: Habit: Aggregates - Made of numerous individual crystals or clusters.
Help on Habit: Habit: Felted - Occurs as minute crystalling aggregates with the form of felt material.
Help on Hardness: Hardness: 3.5 - Copper Penny
Help on Luster: Luster: Adamantine
Help on Streak: Streak: brown
 

Optical Properties of Robertsite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.332 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.393 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2657,KPDmeas= 0.2539,KC= 0.1907
Ncalc = 1.58 - 1.6
Help on Optical Data: Optical Data: Biaxial (-), a=1.775, b=1.82, g=1.82, bire=0.0450, 2V(Calc)=0, 2V(Meas)=8.
 

Calculated Properties of Robertsite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.08 gm/cc
note: Specific Gravity of Robertsite =3.17 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0003857722
Boson Index = 0.9996142278
Help on Photoelectric: Photoelectric: PERobertsite = 9.75 barns/electron
U=PERobertsite x rElectron Density= 30.07 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Robertsite is Not Radioactive
 

Robertsite Classification

Help on  Dana Class: Dana Class: 42.08.04.02 (42)Hydrated Phosphates, etc., Containing Hydroxyl or Halogen
  (42.08)where (AB)7 (XO4)4 Zq � x(H2O)
  (42.08.04)Mitridatite Group
 
42.08.04.01 Mitridatite Ca2Fe3(PO4)3O2•3(H2O) A2/a 2/m
 
42.08.04.02 Robertsite Ca6Mn9(PO4)9O6(H2O)6•3(H2O) A2/a 2/m
 
42.08.04.03 Arseniosiderite Ca2Fe3(AsO4)3O2•3(H2O) A2/a 2/m
Help on  Strunz Class: 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 Robertsite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Robertsite :
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 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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Print or Cut-and-Paste your Robertsite Specimen Label here :

Robertsite

Ca6Mn+++9(PO4)9O6(H2O)6•3(H2O)
Dana No: 42.08.04.02 Strunz No: 08.DH.30
Locality:

 

Notes:

 

 
   
 


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