Olmsteadite Mineral Data (original) (raw)

General Olmsteadite Information

Help on Chemical Formula: Chemical Formula:

KFe++2(Nb,Ta)(PO4)2O2•2(H2O)

Help on Composition: Composition:

Molecular Weight = 523.68 gm

Potassium 7.47 % K 8.99 % K2O

Tantalum 8.64 % Ta 10.55 % Ta2O5

Niobium 13.31 % Nb 19.03 % Nb2O5

Iron 21.33 % Fe 27.44 % FeO

Phosphorus 11.83 % P 27.11 % P2O5

Hydrogen 0.77 % H 6.88 % H2O

Oxygen 36.66 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Help on Empirical Formula: Empirical Formula:

KFe2+2Nb0.75Ta0.25(PO4)2O2•2(H2O)

Help on Environment: Environment:

Found in Nb-Ta bearing pegmatites.

Help on IMA Status: IMA Status:

Approved IMA 1976

Help on Locality: Locality:

Big Chief pegmatite, near Glendale, Pennington County, South Dakota, USA. Link to MinDat.org Location Data.

Help on Name Origin: Name Origin:

Named for Milo Olmstead, micromount mineral collector, Rapid City, South Dakota, USA.

Help on Name Pronunciation: Name Pronunciation:

Olmsteadite + Pronunciation Say OLMSTEADITE

Help on Synonym: Synonym:

ICSD 12138

PDF 35-633

Olmsteadite Image

Click Here for Larger Olmsteadite Image in a New Browser Window Images:

Olmsteadite Crystallography

Help on Axial Ratios: Axial Ratios:

a:b:c =0.7512:1:0.6492

Help on Cell Dimensions: Cell Dimensions:

a = 7.512, b = 10, c = 6.492, Z = 2; V = 487.68 Den(Calc)= 3.57

Help on Crystal System: Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: Pb21m

Help on X Ray Diffraction: X Ray Diffraction:

By Intensity(I/Io): 6.006(1), 3.003(0.7), 3.047(0.6),

Click Here for Large Olmsteadite Structure Window Crystal Structure:

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Help on Above

| | Moore P B , Araki T , Kampf A R , Steele I M , American Mineralogist , 61 (1976) p.5-11, Olmstaedite, K2Fe2[Fe2(Nb,Ta)2O4(H2O)4(PO4)4], a new species, its crystal, structure and relation to vauxite and montgomeryite | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

Physical Properties of Olmsteadite

Help on Cleavage: Cleavage:

{100} Good, {001} Good

Help on Color: Color:

Brown, Reddish brown, Black.

Help on Density: Density:

3.31 - 3.36, Average = 3.33

Help on Diaphaneity: Diaphaneity:

Transparent to Translucent

Help on Fracture: Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Help on Habit: Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Help on Hardness: Hardness:

4 - Fluorite

Help on Luster: Luster:

Subadamantine

Help on Streak: Streak:

olive green

Optical Properties of Olmsteadite

Help on Gladstone-Dale: Gladstone-Dale:

CI meas= -0.116 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.042 (Good) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.218,KPDmeas= 0.2334,KC= 0.2091
Ncalc = 1.69 - 1.75

Help on Optical Data: Optical Data:

Biaxial (+), a=1.725-1.765, b=1.755-1.775, g=1.815-1.835, bire=0.0700-0.0900, 2V(Calc)=46-74, 2V(Meas)=60.

Help on Pleochroism (x): Pleochroism (x):

blue green.

Help on Pleochroism (y): Pleochroism (y):

yellow.

Help on Pleochroism (z): Pleochroism (z):

brown.

Calculated Properties of Olmsteadite

Help on Electron Density: Electron Density:

Bulk Density (Electron Density)=3.41 gm/cc
note: Specific Gravity of Olmsteadite =3.57 gm/cc.

Help on Fermion Index: Fermion Index:

Fermion Index = 0.0047181274
Boson Index = 0.9952818726

Help on Photoelectric: Photoelectric:

PEOlmsteadite = 120.73 barns/electron
U=PEOlmsteadite x relectron= 411.53 barns/cc.

Help on Radioactivity: Radioactivity:

GRapi = 102.84 (Gamma Ray American Petroleum Institute Units)
Concentration of Olmsteadite per GRapi unit = 0.97 (%)

Estimated Radioactivity from Olmsteadite - barely detectable

Olmsteadite Classification

Help on Dana Class: Dana Class:

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

(42.07)where (AB)5 (XO4)3 Zq � x(H2O)

(42.07.11)Olmsteadite Group

42.07.11.01 Olmsteadite KFe2(Nb,Ta)(PO4)2O2•2(H2O) Pb21m mm2

42.07.11.02 Johnwalkite K(Mn,Fe,Fe)2(Nb,Ta)(PO4)2O2((H2O),OH)2 Pb21m mm2

Help on Strunz Class: Strunz Class:

08.DJ.05 08 - PHOSPHATES, ARSENATES, VANADATES

08.D - Phosphates, etc

08.DJ -With large and medium-sized cations, (OH, etc.):RO4 = 1:l

08.DJ.05 Johnwalkite K(Mn,Fe,Fe)2(Nb,Ta)(PO4)2O2((H2O),OH)2 Pb21m mm2

08.DJ.05 Olmsteadite KFe2(Nb,Ta)(PO4)2O2•2(H2O) Pb21m mm2

Other Olmsteadite Information

Help on References: References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana8)

Help on See Also: See Also:

Links to other databases for Olmsteadite :
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
15 - WWW-MINCRYST

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

Olmsteadite

KFe++2(Nb,Ta)(PO4)2O2•2(H2O)
Dana No: 42.07.11.01 Strunz No: 08.DJ.05
Locality:

Notes: