Rietveldit

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Rietveldit
Rietveldite, Bobcookite, Ferricopiapite-805465.jpg
Light brownish-yellow, tufted rietveldite, fused with yellow ferricopiapite and greenish, hygroscopic bob cookite (top left) from the Giveway-Simplot Mine, Red Canyon , San Juan County (Utah) , USA. The white, spherical aggregates are unidentified sulfates. (Field of view 2.2 mm)
General and classification
other names

IMA 2016-081

chemical formula Fe (UO 2 ) (SO 4 ) 2 • 5H 2 O
Mineral class
(and possibly department) 		Sulphates, Selenates, Tellurates, Chromates, Molybdates and Wolframates
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-pyramidal; mm 2
Space group Pmn 2 1 (No. 31)Template: room group / 31
Lattice parameters a  = 12.9577 (9)  Å ; b  = 8.3183 (3) Å; c  = 11.2971 (5) Å
Formula units Z  = 4
Physical Properties
Mohs hardness ≈ 2
Density (g / cm 3 ) calculated: 3.37
Cleavage good after {010}; clearly after {100} and {001}
Break ; Tenacity curved fracture surfaces; brittle
colour brownish-yellow to yellowish-beige
Line color White
transparency transparent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.570 (1)
n β  = 1.577 (1)
n γ  = 1.586 (1)
Birefringence δ = 0.016
Optical character biaxial positive
Axis angle 2V = 82 ° (measured), 83.3 ° (calculated)
Other properties
Chemical behavior easily soluble in water

Rietveldite is a very rarely occurring mineral from the mineral class of " sulfates (selenates, tellurates, chromates, molybdates and tungstates)" with the chemical composition Fe (UO 2 ) (SO 4 ) 2 · 5H 2 O and is therefore chemically water-containing Iron - uranyl sulfate.

Rietveldite crystallizes in the orthorhombic crystal system and has so far only been found in the form of tiny crystal leaves stretched along the c-axis up to about 0.5 mm in length and powdery aggregates from brownish-yellow to yellowish-beige in color. The crystals are transparent to translucent and have a glass-like sheen on the surface .

Etymology and history

The mineral was named after the Dutch crystallographer Hugo Rietveld (1932-2016), the father of the Rietveld refinement , which provides structural data such as the parameters of unit cells from powder X-ray diffraction patterns.

Rietveldit was analyzed and scientifically described by a team of mineralogists consisting of Anthony R. Kampf, Jiří Sejkora, Thomas Witzke , Jakub Plášil, Jiří Čejka, Barbara P. Nash and Joe Marty, who submitted their analyzes and named them to the International Mineralogical Association in 2016 (IMA) submitted for review. Rietveldit was recognized as an independent mineral in the same year. The new discovery was then published in June 2017 in the "Journal of Geosciences".

The type locality is the "Giveaway-Simplot" pits in the White Canyon district ( San Juan County ) in the US state of Utah, Jáchymov ( Sankt Joachimsthal ) in the Czech region of Okres Karlovy Vary ( Karlsbad ) and "Willi Agatz" near Dresden in Saxony ( Germany), as the type material required for the analysis comes from all three sites.

Type material of the mineral are in the Natural History Museum of Los Angeles County in the USA under catalog no. 66291 and 66292, in the Technical University Bergakademie Freiberg in Germany under catalog no. 84140 and in the mineralogical-petrological department of the Prague National Museum in the Czech Republic under catalog no. P1N 45564 kept.

classification

Rietveldit was only recognized by the IMA as an independent mineral in 2016. An exact group assignment in the 9th edition of Strunz's mineral systematics , which was last updated in 2009, is therefore not yet known. However, since the mineral is chemically related to deliensite (Fe [UO 2 | OH | SO 4 ] 2 · 3H 2 O; IMA 1996-013), which, due to its composition, belongs to the mineral class of “sulfates (selenates, tellurates, chromates, molybdates and Wolframate) "and there in the subdivision of uranyl sulfates with medium-sized cations with the system no. 7.EB can be found, Rietveldit will probably also be sorted there.

Crystal structure

Rietveldite crystallizes orthorhombically in the space group Pmn 2 1 (space group no. 31) with the lattice parameters a  = 12.9577 (9)  Å ; b  = 8.3183 (3) Å; c  = 11.2971 (5) Å and 4 formula units per unit cell . Template: room group / 31

Rietveldite is structurally related to svornostite (K 2 Mg [(UO 2 ) (SO 4 ) 2 ] 2 · 8H 2 O).

properties

The mineral is radioactive due to its uranium content in the form UO 3 of up to 47.32% .

Rietveldit is easily soluble in water even at room temperature.

Education and Locations

Rietveldit, gypsum and ferricopiapit on an asphalt matrix

Rietveldit forms secondary and found himself on asphalt in paragenesis with Ferricopiapit , gypsum , Römerit and Shumwayit and with pyrite impregnated sandstone in association with gypsum, Halotrichit and Römerit.

Apart from its type localities “Willi Agatz” mine in Saxony (Germany), Jáchymov ( Sankt Joachimsthal ) in the Czech Republic and “Giveaway-Simplot” mine in the US state of Utah, no other sites for Rietveldit are known so far (as of 2017).

Precautions

Due to the toxicity and the strong radioactivity of the mineral, mineral samples should only be kept in dust- and radiation-tight containers, but especially never in living rooms, bedrooms or work rooms. Absorption into the body ( incorporation , ingestion ) should also be prevented in any case and, for safety, direct body contact should be avoided and face masks and gloves should be worn when handling the mineral.

See also

literature

  • U. Hålenius, F. Hatert, M. Pasero, SJ Mills: IMA Commission on New Minerals, Nomenclature and Classification (CNMNC). Newsletter 34 . In: Mineralogical Magazine . tape 80 , no. 7 , December 2016, p. 1315-1321 ( main.jp [PDF; 97 kB ; accessed on February 12, 2017]).
  • Anthony R. Kampf, Jiří Sejkora, Thomas Witzke , Jakub Plášil, Jiří Čejka, Barbara P. Nash, Joe Marty: Rietveldite, Fe (UO 2 ) (SO 4 ) 2 (H 2 O) 5 , a new uranyl sulfate mineral from Giveaway-Simplot mine (Utah, USA), Willi Agatz mine (Saxony, Germany) and Jáchymov (Czech Republic) . In: Journal of Geosciences . tape 62 , no. 2 , 2017, p. 107–120 , doi : 10.3190 / jgeosci.236 ( jgeosci.org [PDF; 1.1 MB ; accessed on June 25, 2017]).

Web links

Individual evidence

  1. ↑ a b c d e f g h i j k l Anthony R. Kampf, Jiří Sejkora, Thomas Witzke , Jakub Plášil, Jiří Čejka, Barbara P. Nash, Joe Marty: Rietveldite, Fe (UO 2 ) (SO 4 ) 2 (H 2 O) 5 , a new uranyl sulfate mineral from Giveaway-Simplot mine (Utah, USA), Willi Agatz mine (Saxony, Germany) and Jáchymov (Czech Republic) . In: Journal of Geosciences . tape 62 , no. 2 , 2017, p. 107–120 , doi : 10.3190 / jgeosci.236 ( jgeosci.org [PDF; 1.1 MB ; accessed on June 25, 2017]).
  2. ↑ a b c d e f g h Mindat - Rietveldite
  3. ↑ List of publications in the Journal of Geosciences, Volume 62, No. 2 of June 7, 2017
  4. ^ IMA / CNMNC List of Mineral Names; 2009 (PDF 1.8 MB)
  5. ^ Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  414 .
  6. ↑ Find location list for Rietveldit at the Mineralienatlas and at Mindat