Olmsteadite
A valid IMA mineral species
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About Olmsteadite
Formula:
KFe2+2(Nb5+,Ta5+)(PO4)2O2 · 2H2O
Colour:
Deep brown, red-brown to black
Lustre:
Sub-Adamantine
Hardness:
4
Specific Gravity:
3.31 - 3.36
Crystal System:
Orthorhombic
Name:
Named in 1976 by Paul Brian Moore, Takaharu Araki, Anthony R. Kampf, and Ian M. Steele in honor of Milo C. Olmstead [December 5, 1909, Gillett Grove, Iowa, USA - June 4, 2005, Rapid City, South Dakota, USA], amateur collector of microscopic minerals, who called attention to the mineral.
Unique Identifiers
Mindat ID:
2986
Long-form identifier:
mindat:1:1:2986:1
GUID
(UUID V4):
(UUID V4):
9f47f806-0411-42f3-b64b-d90d463c5910
IMA Classification of Olmsteadite
Approved
IMA Formula:
KFe2+2NbO2(PO4)2 · 2H2O
Approval year:
1974
Classification of Olmsteadite
8.DJ.05
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
J : With large and medium-sized cations, (OH, etc.):RO4 = 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
J : With large and medium-sized cations, (OH, etc.):RO4 = 1:1
42.7.11.1
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
22.5.13
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference |
|---|---|---|
| Osd | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Pronunciation of Olmsteadite
Pronunciation:
| Play | Recorded by | Country |
|---|---|---|
| Jolyon Ralph | United Kingdom |
Physical Properties of Olmsteadite
Sub-Adamantine
Transparency:
Translucent
Comment:
may be bronzy
Colour:
Deep brown, red-brown to black
Streak:
Olive-green
Hardness:
4 on Mohs scale
Density:
3.31 - 3.36 g/cm3 (Measured) 3.41 g/cm3 (Calculated)
Optical Data of Olmsteadite
Type:
Biaxial (+)
RI values:
nα = 1.725 - 1.765 nβ = 1.755 - 1.775 nγ = 1.815 - 1.835
2V:
Measured: 60° , Calculated: 46° to 74°
Max Birefringence:
δ = 0.090
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v moderate
Pleochroism:
Visible
Comments:
X = blue-green or dark blue; Y = yellow or light brown; Z = brown to dark brown.
Chemistry of Olmsteadite
Mindat Formula:
KFe2+2(Nb5+,Ta5+)(PO4)2O2 · 2H2O
Crystallography of Olmsteadite
Crystal System:
Orthorhombic
Class (H-M):
mm2 - Pyramidal
Cell Parameters:
a = 7.512(1) Å, b = 10.000(3) Å, c = 6.492(2) Å
Ratio:
a:b:c = 0.751 : 1 : 0.649
Unit Cell V:
487.68 ų (Calculated from Unit Cell)
Z:
1
Comment:
Space Group: P b21m
Crystallographic forms of Olmsteadite
Crystal Atlas:
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Olmsteadite - Tabular {001}
Olmsteadite - Tabular {100}
3d models and HTML5 code kindly provided by
www.smorf.nl.
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Data courtesy of the American Mineralogist Crystal Structure Database. Click on an AMCSD ID to view structure
| ID | Species | Reference | Link | Year | Locality | Pressure (GPa) | Temp (K) |
|---|---|---|---|---|---|---|---|
| 0000485 | Olmsteadite | Moore P B, Araki T, Kampf A R, Steele I M (1976) Olmstaedite, K2Fe2[Fe2(Nb,Ta)2O4(H2O)4(PO4)4], a new species, its crystal structure and relation to vauxite and montgomeryite American Mineralogist 61 5-11 |  | 1976 | 0 | 293 |
CIF Raw Data - click here to close
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 6.006 Å | (10) |
| 3.03 Å | (7) |
| 3.047 Å | (6) |
| 2.856 Å | (6) |
| 7.512 Å | (5) |
| 6.492 Å | (5) |
| 4.409 Å | (5) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 22 : Hydration and low-𝑇 subsurface aqueous alteration (see also #23) |
Type Occurrence of Olmsteadite
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 135924.
Associated Minerals at Type Locality:
Reference:
Moore, P. B., Araki, T., Kampf, A. R. & Steele, I. M. (1976) Olmsteadite, K2Fe2+2[Fe2+2(Nb,Ta)5+2O4(H2O)4(PO4)4], a new species, its crystal structure and relation to vauxite and montgomeryite. American Mineralogist, 61, 5-11.
Synonyms of Olmsteadite
Other Language Names for Olmsteadite
Related Minerals - Strunz-mindat Grouping
| 8.DJ.05 | Johnwalkite | K(Mn2+,Fe2+,Fe3+)2(Nb5+,Ta5+)(PO4)2O2 · 2(H2O,OH) |
| 8.DJ.10 | Gatumbaite | CaAl2(PO4)2(OH)2 · H2O |
| 8.DJ.15 | Camgasite | CaMg(AsO4)(OH) · 5H2O |
| 8.DJ.20 | Phosphofibrite | (H2O,K)3.5Fe8(PO4)6(OH)7 · 5H2O |
| 8.DJ.20 | Meurigite-K | KFe3+8(PO4)6(OH)7 · 6.5H2O |
| 8.DJ.20 | Meurigite-Na | NaFe3+8(PO4)6(OH)7 · 6.5H2O |
| 8.DJ.25 | Jungite | Ca2Zn4Fe3+8(PO4)9(OH)9 · 16H2O |
| 8.DJ.30 | Wycheproofite | NaAlZr(PO4)2(OH) · H2O |
| 8.DJ.35 | Ercitite | Na2Mn3+2(PO4)2(OH)2 · 4H2O |
| 8.DJ.40 | Mrázekite | Bi2Cu3(PO4)2O2(OH)2 · H2O |
| 8.DJ.45 | Attikaite | Ca3Cu2Al2(AsO4)4(OH)4 · 2H2O |
| 8.DJ.50 | Mengeite | Ba(Mg,Mn2+)Mn3+4(PO4)4(OH)4 · 4H2O |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Olmsteadite
mindat.org URL:
https://www.mindat.org/min-2986.html
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References for Olmsteadite
Localities for Olmsteadite
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
USA (TL) | |
| Moore et al. (1976) |
| Moore et al. (1976) | |
| Anthony et al. (2016) |
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White Cap Mine, Keystone, Keystone Mining District, Pennington County, South Dakota, USA