Mandarinoite
| Mandarinoite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1977-049 |
| chemical formula | Fe 3+ 2 (SeO 3 ) 3 · 6H 2 O |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4th century 15 ( 8th edition : IV / K.08) 03/34/04/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 16.81 Å ; b = 7.88 Å; c = 10.02 Å β = 98.3 ° |
| Formula units | Z = 4 |
| Frequent crystal faces | {100}, {110}, {011}, { 1 01} |
| Twinning | after (100) |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 2.93 (3); calculated: 3.04 |
| Cleavage | Segregation after {100} |
| Break ; Tenacity | not defined |
| colour | light green, yellowish green, greenish white, almost colorless in thin layers |
| Line color | very light green, pale green |
| transparency | transparent to translucent |
| shine | Glass gloss to weak greasy gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.715 n β = 1.797 to 1.800 n γ = 1.860 to 1.870 |
| Birefringence | δ = 0.145 to 0.155 |
| Optical character | two-axis negative |
| Axis angle | 2V = 80 to 85 ° (measured); calculated: 80 ° |
Mandarinoite is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the monoclinic crystal system with the composition Fe 3+ 2 (SeO 3 ) · 6H 2 O, so it is chemically a hydrous iron - selenite .
Mandarinoite only develops millimeter-sized crystals with a tabular, sword-like habit , which are stretched along the c-axis and mostly arranged in rosette-shaped mineral aggregates . The surfaces of the transparent to translucent crystals have a glass-like sheen . Its color varies mainly between light green, yellowish green and greenish white, but it appears almost colorless in thin layers. Mandarinoite leaves a pale green tinge on the chalkboard .
Etymology and history
Mandarinoite was first discovered in 1977 in the silver mine "Virgen de Surumi" (also Pacajake or Pakajake , named after the Pakajake Canyon ), which is located about twenty kilometers northeast of Colquechaca in the Bolivian Department of Potosí . The mineral was described in 1978 by Pete J. Dunn , Donald R. Peacor and Bozidar Darko Sturman , who named it after the American-Canadian mineralogist and former curator of the Royal Ontario Museum Joseph Anthony Mandarino (1929-2007).
Type material of the mineral is stored in the Royal Ontario Museum in Canada (register no. 35273), at Harvard University in Massachusetts (register no. 111364 and 111368D) and in the National Museum of Natural History in Washington (register no. 142878) .
classification
Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the mandarinoite belonged to the mineral class of "oxides and hydroxides" and there to the department of " sulfites , selenites and tellurites ", where it was the only member of the unnamed group IV / K.08 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies the mandarinoite in the expanded division of “arsenites, antimonides, bismuthides, sulfites, selenites and tellurites”. However, this is further subdivided according to the possible presence of additional anions and / or water of crystallization , so that the mineral can be classified in the sub-section “Selenite without additional anions; with H 2 O ”can be found, where it is the only member of the unnamed group 4.JH.15 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the mandarinoite to the class of " sulfates , chromates and molybdates " and there to the category of "selenites, tellurites and sulfites". Here he is to be found as the only member of the unnamed group 34.03.04 within the sub-section “Selenites - Tellurites - Sulphites”.
Education and Locations
Mandarinoit formed in the oxidation zone selenium-rich ore - deposits . As accompanying minerals may include Chalkomenit , Chlorargyrite , goethite , Krutaite , Penroseite , Poughit , pyrite , quartz and siderite occur.
As a rare mineral formation, mandarinoite could only be detected at a few sites, whereby so far (as of 2013) a little more than 10 sites are known. In addition to its type locality "Virgen de Surumi" in the province of Chayanta, the mineral was also found in Bolivia in the mine "El Dragón" in the province of Antonio Quijarro .
Other well-known sites include Cobar in Australia; Enshi in China; Ojojona in Honduras; Villaputzu in Italy; De Lamar (Owyhee County, Idaho), Elko and Maggie Creek (Eureka County, Nevada) and Polar Mesa (Grand County, Utah) in the United States, and Skouriotissa in Cyprus .
Crystal structure
Mandarinoite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 16.81 Å ; b = 7.88 Å; c = 10.02 Å and β = 98.3 ° as well as 4 formula units per unit cell .
See also
literature
- Pete J. Dunn, Donald R. Peacor, BD Sturman: Mandarinoite, A New Ferriciron Selenite from Bolivia , In: The Canadian Mineralogist , Volume 16 (1978), pp. 605-609
- Michael Fleischer, JA Mandarino, Adolf Pabst: New Mineral Names , In: American Mineralogist , Volume 65 (1980), pp. 205–210 ( PDF 758 kB ; Mandarinoite p. 2)
- Frank C. Hawthornee: The crystal structure of Mandarinoite, Fe 3+ Se 3 O 9 · 6H 2 O , In: Canadian Mineralogist , Volume 22 (1984), pp. 475-480 ( PDF 503.2 kB )
Web links
- Mineral Atlas: Mandarinoite (Wiki)
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. 273 .
- ↑ Webmineral - Mandarinoite
- ↑ a b Mandarinoite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68.5 kB )
- ↑ a b c Mindat - Mandarinoite
- ↑ Mindat - Number of localities for mandarinoite
- ↑ Find location list for mandarinoites in the Mineralienatlas and in [Mindat]