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|System:||Hexagonal||Colour:||Bright green, apple ...|
|Name:||Named by Dietrich Ludwig Gustav Karsten in 1800 for the Greek word for "fat", in allusion to the mineral's appearance. Pimelite was determined to be a smectite as early as 1938 [also American Mineralogist 51:279 . Later erroneously ascribed to nickel-rich talc (American Mineralogist 64:615 ). Both nickel-bearing talc, intermediate nickeloan nontronite, and nickel dominant smectite occur at the type locality. A re-validation research project has begun.|
A significant literature exists verifying that pimelite is nickel-dominant smectite, although there are studies which misidentified the starting material as "pimelite" and reached erroneous conclusions. Often thought to be a coloring agent in chrysoprase, but probably rarely present in that material.
Dark grass to forest green masses of pimelite are found in color zoned pods (to 1 meter) with yellow green nickeloan nontronite associated with red brown hematite stained nontronite and adjacent to bright white montmorillonite pods in a weathering profile.
Classification of Pimelite
|Strunz 8th edition ID:||8/H.09-65|
8 : Silicates
H : Phyllosilicates (layered), Tetragonal or pseudotetragonal layered structures [Si4O10]4- and others
09 : Talc series
|Dana 8th edition ID:||71.3.1b.5|
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
3 : Sheets of 6-membered rings with 2:1 clays
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Physical Properties of Pimelite
|Colour:||Bright green, apple green, yellow-green|
|Streak:||White to pale green|
|Density (measured):||2.23-2.98 g/cm3|
|Density (calculated):||2.68 g/cm3|
Crystallography of Pimelite
|Cell Parameters:||a = 5.256Å, c = 14.822Å|
|Ratio:||a:c = 1 : 2.82|
|Unit Cell Volume:||V 354.61 Å³ (Calculated from Unit Cell)|
|Comment:||Expands to 17.35 A using glycol|
|X-Ray Powder Diffraction:|
Optical Data of Pimelite
|RI values:||nα = 1.592 nγ = 1.615|
|2V:||Measured: 30° to 80°|
|Maximum Birefringence:||δ = 0.023|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
|Optical Extinction:||Can appear isotropic|
|Comments:||Pale green colorless to light yellow green|
Chemical Properties of Pimelite
|Essential elements:||H, Ni, O, Si|
|All elements listed in formula:||H, Ni, O, Si|
|Analytical Data:||Analysis of magnesian pimelite from the type locality (various studies including The Hydrous Nickel-Magnesium Silicates - The Garnierite Group, George T. Faust, American Mineralogist (1966) v 51, 279-298.)|
SiO2 (47.20) NiO (27.66) MgO (11.42) Al2O3 (0.22) Fe2O3 (0.20) CaO (0.16) H2O+ (9.38) H2O- (3.64)
Relationship of Pimelite to other Species
|Member of:||Smectite Group|
|Other Members of Group:|
|Related Minerals - Strunz Grouping):|
Other Names for Pimelite
|Fluorescence in UV light:||Not fluorescent|
|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 Pimelite
Spangenberg, Kurt, 1938, Die wasserhaltigen Nickelsilicate, Cent. Mineral. Abt. A., p. 360-364.
George T. Faust,, 1966, The Hydrous Nickel-Magnesium Silicates - The Garnierite Group, American Mineralogist, v 51, 279-298.
Manceau, Alain and Calas, Georges, 1985, Heterogeneous Distribution of Nickel in Hydrous Silicates from New Caledonia Ore Deposits, American Mineralogist (1985): 70: 549-558. [Studies not performed on "pimelite".]
Clays and Clay Minerals (1987): 35: 1.
Burke, Ernest A.J. (2007) A Mass Discreditation of GQN Minerals. Canadian Mineralogist: 44(6): 1557-1560.
Internet Links for Pimelite
Localities for Pimelite
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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Locality Updated: Proserpina reservoir, Mérida, Badajoz, Extremadura, SpainFrom Joan Rosell, 5th Dec 2013 09:46:23