Mundit
| Mundit | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1980-075 |
| chemical formula | Al [(UO 2 ) 3 | (OH) 3 | (PO 4 ) 2 ] · ≈5.5H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.EC.30 42.07.13.01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m or orthorhombic-pyramidal; mm 2 |
| Space group | Pmcn (No. 62, position 5) |
| Lattice parameters | a = 17.08 Å ; b = 30.98 Å; c = 13.76 Å |
| Formula units | Z = 16 |
| Physical Properties | |
| Mohs hardness | 2 to 3 |
| Density (g / cm 3 ) | measured:> 4.05; calculated: 4.295 |
| Cleavage | completely according to {010}, {100}, {001} |
| Break ; Tenacity | not defined |
| colour | golden yellow to light yellow |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.620 n β = 1.682 n γ = 1.688 |
| Birefringence | δ = 0.068 |
| Optical character | biaxial negative |
| Axis angle | 2V = 33 ° (measured); 32 ° (calculated) |
| Other properties | |
| Special features | fluorescence |
Mundit is an extremely rare mineral from the mineral class of " phosphates , arsenates and vanadates " with the composition Al [(UO 2 ) 3 | (OH) 3 | (PO 4 ) 2 ] · ≈5.5H and therefore chemically one water-containing aluminum - uranyl phosphate with additional hydroxide ions .
Mundit crystallizes in the orthorhombic crystal system , but only develops tiny, rectangular-tabular crystals up to about 0.5 millimeters in size. These are transparent and from golden yellow to light yellow in color with a glass-like sheen on the surfaces. Mundit leaves a white line on the whiteboard .
Etymology and history
Mundit was first discovered in the "Kobokobo" pegmatites near Mwenga in the Lusungu River District of the Congolese province of Sud-Kivu . It was first described in 1981 by Michel Deliens and Paul Piret , who named the mineral after the Belgian radiochemist Walter Mund (1892–1956).
Six pieces (a few milligrams) of the mineral are kept as type material in the “Musee Royale Afrique Centrale” of the Belgian municipality of Tervuren under catalog number RGM 11.888.
classification
Since the Mundit was only recognized as an independent mineral in 1980, it is not yet listed in the 8th edition of the mineral classification according to Strunz , which has been outdated since 1977 . Only in the Lapis mineral directory , which was revised and updated in 2018 by Stefan Weiß, which is still based on this classic system from Karl Hugo Strunz out of consideration for private collectors and institutional collections , the mineral received the system and mineral number. VII / E.07-20 . In the "Lapis system" this corresponds to the class of "Phosphates, Arsenate and Vanadates" and there the section "Uranyl Phosphates / Arsenates and Uranyl Vanadates with [UO 2 ] 2+ - [PO 4 ] / [AsO 4 ] 3- and [UO 2 ] 2+ - [V 2 O 8 ] 6- , with isotypic vanadates (Sincosit-R.) “, Where mundite together with althupite , arsenovan sea log , arsenuranylite , bergenite , dewindtite , dumontite , francoisite (Ce ) , Françoisit- (Nd) , Hügelite , Kamitugait , Kivuit , Metavanmeer log , Nielsbohrit , Phuralumit , Phosphuranylit , Phurcalit , Renardit , Vanmeersscheit and Yingjiangit form an independent but unnamed group.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and was updated by the International Mineralogical Association (IMA) until 2009, initially classifies Mundit more generally in the “uranyl phosphates and arsenates” department. However, this is further subdivided according to the molar ratio of the uranium oxide (UO 2 ) to the phosphate or arsenate complex (RO 4 ), so that the mineral can be found in the sub-section "UO 2 : RO 4 = 3: 2" according to its composition , where it is the only member of the unnamed group 8.EC.30 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Mundit to the class of "phosphates, arsenates and vanadates" and there to the category of "water-containing phosphates, etc., with hydroxyl or halogen ". Here he is to be found as the only member in the unnamed group July 42, 2013 within the subdivision of "Water-containing phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 3 Z q × x (H 2 O)".
Crystal structure
Mundit crystallizes orthorhombically in the space group Pmcn (space group no. 62, position 5) or P 2 1 cn (no. 33, position 4) with the lattice parameters a = 17.08 Å ; b = 30.98 Å and c = 13.76 Å and 16 formula units per unit cell .
properties
The mineral is by its uranium content of about 61% (69.35% UO 2 as a very strong) radioactively classified and has a specific activity of about 109.4 k Bq / g (compared to natural potassium 0.0312 kBq / g ).
Mundit shows a light green fluorescence under UV light , similar to that of neon-colored highlighters .
Education and Locations
Mundite forms in the oxidation zone of uranium-containing, complex granite - pegmatite . Eylettersite , phuralumite , upalite , ranunculite and threadgoldite appear as accompanying minerals .
So far (as of 2013) the mineral could only be detected at its type locality Kobokobo in the Democratic Republic of the Congo.
Precautions
Due to the strong radioactivity of the mineral, Mundit 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
- Michel Deliens, Paul Piret: Les Phosphates d'uranyl et d'aluminium de Kobokobo, V. Mundite, a new mineral . In: Bulletin de minéralogie . tape 104 , no. 5 , 1981, pp. 669-671 (French).
- Michael Fleischer , Louis J. Cabri, GY Chao, JA Mandarino, Adolf Pabst: New Mineral Names . In: American Mineralogist . tape 67 , 1982, pp. 621–624 (English, rruff.info [PDF; 545 kB ; accessed on October 27, 2019]).
Web links
- Mineral Atlas: Mundit (Wiki)
Individual evidence
- ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: September 2019. (PDF 2672 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, September 2019, accessed October 27, 2019 .
- ↑ a b c d e 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. 527 (English).
- ↑ a b c Mundite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 65 kB ; accessed on October 27, 2019]).
- ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ a b David Barthelmy: Mundite Mineral Data. In: webmineral.com. Retrieved October 27, 2019 .
- ↑ a b c d e f Mundite. In: mindat.org. Hudson Institute of Mineralogy, accessed October 27, 2019 .
- ↑ Catalog of Type Mineral Specimens - M. (PDF 124 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed October 27, 2019 .
- ↑ Michael Fleischer , Louis J. Cabri, GY Chao, JA Mandarino, Adolf Pabst: New Mineral Names . In: American Mineralogist . tape 67 , 1982, pp. 621–624 (English, rruff.info [PDF; 545 kB ; accessed on October 27, 2019]).
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed October 27, 2019 .