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|Name:||Honoring Milo Olmstead, Rapid City, South Dakota, USA, amateur collector of microscopic minerals, who called attention to the mineral.|
The Fe analogue of johnwalkite.
Classification of Olmsteadite
|IMA status:||Approved 1974|
|Strunz 8th edition ID:||7/D.39-10|
|Nickel-Strunz 10th (pending) edition ID:||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
|Dana 8th edition ID:||126.96.36.199|
42 : HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
7 : (AB)2(XO4)Zq·xH2O
|Hey's CIM Ref.:||22.5.13|
22 : Phosphates, Arsenates or Vanadates with other Anions
5 : Phosphates, arsenates or vanadates with chromate, molybdate, niobate or tantalate
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Type Occurrence of Olmsteadite
|Type Locality:||Big Chief Mine (Johnson pegmatite), Glendale, Keystone District, Pennington Co., South Dakota, USA|
|Place of Conservation of Type Material:||National Museum of Natural History, Washington, D.C., USA, 135924.|
|Year of Discovery:||1976|
Physical Properties of Olmsteadite
Crystallography of Olmsteadite
|Cell Parameters:||a = 7.47Å, b = 10.03Å, c = 6.53Å|
|Ratio:||a:b:c = 0.745 : 1 : 0.651|
|Unit Cell Volume:||V 489.25 Å³ (Calculated from Unit Cell)|
About Crystal AtlasYou may need to scroll this box using your mouse to view the full instructions.
The mindat.org Crystal Atlas allows you to view a selection of crystal drawings of real and idealised crystal forms for this mineral and, in certain cases, 3d rotating crystal objects. You need Java to see these. You can download Java for free - click here to download Java
The 3d models and java code are kindly provided by www.smorf.nl. You can control the movement of the models by holding down the left mouse-button over the 3d model and moving your mouse. Keyboard controls are:
Optical Data of Olmsteadite
|RI values:||nα = 1.725 - 1.765 nβ = 1.755 - 1.775 nγ = 1.815 - 1.835|
|2V:||Measured: 60° , Calculated: 46° to 74°|
|Maximum Birefringence:||δ = 0.090|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Dispersion:||r > v moderate|
Chemical Properties of Olmsteadite
|Essential elements:||Fe, H, K, Nb, O, P|
|All elements listed in formula:||Fe, H, K, Nb, O, P, Ta|
Relationship of Olmsteadite to other Species
|Related Minerals - Nickel-Strunz Grouping):|
|Related Minerals - Hey's Index Grouping:|
Other Names for Olmsteadite
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Olmsteadite
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.
Internet Links for Olmsteadite
Localities for Olmsteadite
The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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