Whitmoreit
| Whitmoreit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1974-009 |
| chemical formula | Fe 2+ Fe 3+ 2 [OH | PO 4 ] 2 · 4H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.DC.15 ( 8th edition : VII / D.08) 11.42.18.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 10.00 Å ; b = 9.73 Å; c = 5.47 Å β = 93.8 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {110}, {100}, {011}, {021}, {112} |
| Physical Properties | |
| Mohs hardness | 3 |
| Density (g / cm 3 ) | measured: 2.87 (1); calculated: 2.85 |
| Cleavage | good after {100} |
| colour | dark brown to greenish brown |
| Line color | Please complete |
| transparency | translucent |
| shine | Glass gloss to weak diamond gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.670 to 1.676 n β = 1.712 to 1.725 n γ = 1.745 to 1.850 |
| Birefringence | δ = 0.075 to 0.174 |
| Optical character | biaxial negative |
| Axis angle | 2V = measured: 60 to 65 °; calculated: 62 ° |
| Pleochroism | visible: X = Y = light greenish brown to yellow Z = dark greenish brown to yellowish green |
Whitmoreit is a rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition Fe 2+ Fe 3+ 2 [OH | PO 4 ] 2 · 4H 2 O, so it is a water-containing iron phosphate with additional hydroxide ions .
Whitmoreit is translucent and develops only small crystals up to about two millimeters in size with a needle-like to prismatic habit and dark brown to greenish-brown color. Usually these are arranged in the form of fan-shaped, radial-rayed or tufted to spherical mineral aggregates . The crystal surfaces have a glass-like to slightly diamond-like sheen . Its Mohs hardness of 3 corresponds to that of the reference mineral calcite .
Etymology and history
Whitmoreit was first discovered in the “Palermo No. 1 ”near Groton in Grafton County , New Hampshire, USA. It was described in 1974 by Paul Brian Moore , Anthony Robert Kampf and Anthony J. Irving, who named the mineral in honor of the mine owner Robert William Whitmore (* 1936).
Type material of the mineral is kept in the National Museum of Natural History in Washington, DC (Register No. 128069).
classification
In the outdated, but partly still in use 8th edition of the mineral systematics according to Strunz , the Whitmoreit belonged to the department of "Water-containing phosphates with foreign anions ", where together with Arthurite , Bendadaite , Cobaltarthurite , Earlshannonite , Kleemanite , Mapimite and Ojuelaite, it created the "Arthurite- Group "with the system no. VII / D.08 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns Whitmoreit to the department of “Phosphates etc. with additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions (OH etc.) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral according to its composition in the subsection “With exclusively medium-sized cations; (OH etc.): RO 4 = 1: 1 and <2: 1 "can be found, where it is named after the" Whitmoreit Group "with the system no. 8.DC.15 and the other members Arthurite, Bendadaite, Cobalt Arthurite, Earlshannonite, Kunatite and Ojuelaite.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Whitmoreit to the class of "phosphates, arsenates and vanadates" and there in the category of "water-containing phosphates etc., with hydroxyl or halogen". Here he is the namesake in the " Whitmoreit Group " with the system no. 11/22/18 within the subsection “Water-containing phosphates etc., with hydroxyl or halogen with (AB) 4 (XO 4 ) 3 Z q × x (H 2 O)”.
Crystal structure
Whitmoreit crystallizes isostructurally (with the same structure type ) with bendadaite in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 10.00 Å ; b = 9.73 Å; c = 5.47 Å and β = 93.8 ° as well as two formula units per unit cell .
Education and Locations
Whitmoreit forms secondarily through hydrothermal weathering from triphylene in granitic pegmatites . In addition to triphyline, beraunite , laueit , ludlamite , mitridatite , siderite , strunzite and ushkovite can also occur as accompanying minerals .
As a rare mineral formation, Whitmoreit could only be detected at a few sites, with around 30 sites being known to date (as of 2013). In addition to its type locality , the “Palermo No. 1 ”, the mineral was found in other pits near Groton and Alexandria in Grafton County and at Walpole and Alstead in New Hampshire. In addition, there appeared in the US in various pits and quarries in East Hampton in Middlesex County (Connecticut) , Newry and Paris in Oxford County (Maine) and in Fourmile near Custer in Custer County, Glendale and Keystone in Pennington County (South Dakota) revealed .
In Germany, Whitmoreit is known so far only from the Hennenkobel ( Hühnerkobel ) and from Pleystein and Hagendorf near Waidhaus in Bavaria.
The only known site in Switzerland so far is in the Pontetal near Brissago TI in the canton of Ticino.
Other previously known sites include Glen Wills ( Victoria ) in Australia, Blaton in Belgium, Sapucaia do Norte ( Minas Gerais ) in Brazil, Le Bosc ( Occitania ) in France, Vestreno (Lombardy) in Italy, in the Owl Mountains (Sowie Mountains) , Góry Sowie) in Poland, Bendada in Portugal, in Bohemia and Moravia in the Czech Republic and St Agnes (Cornwall) in the United Kingdom.
See also
literature
- Paul Brian Moore, Anthony Robert Kampf, Anthony J. Irving: Whitmoreite, Fe 2+ Fe 3+ 2 (OH) 2 (H 2 O) 4 [PO 4 ] 2 , a new species: its description and atomic arrangement. In: American Mineralogist. Volume 59, 1974, pp. 900–905 ( PDF 636.7 kB )
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th, revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 640 .
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 647 (first edition: 1891).
Web links
- Mineral Atlas: Whitmoreit (Wiki)
- Database-of-Raman-spectroscopy - Whitmoreite
- American-Mineralogist-Crystal-Structure-Database - Whitmoreite
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 498 .
- ↑ Webmineral - Whitmoreite
- ↑ a b c Whitmoreite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001.
- ↑ a b c d e f Mindat - Whitmoreite
- ↑ Mindat - Number of localities for Whitmoreit
- ↑ Find location list for Whitmoreit at the Mineralienatlas and at Mindat