Althupite
| Althupite | |
|---|---|
| General and classification | |
| other names |
IMA 1986-003 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates - uranyl phosphates |
|
System no. to Strunz and to Dana |
8.EC.25 04.42.13.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 10.95 Å ; b = 18.57 Å; c = 13.50 Å, α = 72.6 °; β = 68.2 °; γ = 84.2 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | tabular after {100}, end faces {011} and {021} |
| Physical Properties | |
| Mohs hardness | 3 to 4 |
| Density (g / cm 3 ) | measured: 3.9 (1); calculated: 3.98 |
| Cleavage | Well |
| colour | yellow |
| Line color | yellowish white |
| transparency | transparent |
| shine | Glass gloss |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n α = 1.620 n β = 1.661 n γ = 1.665 |
| Birefringence | δ = 0.045 |
| Optical character | biaxial negative |
| Axis angle | 2V = 31 ° (measured), 34 ° (calculated) |
| Pleochroism | visible: X = very light yellow Y = Z = yellow |
Althupite is a very rarely occurring mineral from the mineral class of "phosphates, arsenates and vanadates" with the chemical composition AlTh (UO 2 ) 7 (PO 4 ) 4 O 2 (OH) 5 · 15H 2 O or in the crystal-chemical structural formula notation Thal [O 2 | (OH) 5 | (UO 2 ) 7 | (PO 4 ) 4 ] · 15H 2 O. Althupit is thus chemically seen a hydrous aluminum - thorium - uranyl - phosphate with additional hydroxide .
Althupite crystallizes in the triclinic crystal system , but develops only tiny, thin tabular crystals up to about 0.1 mm in size, which are usually arranged in parallel groups. A glass-like sheen can be seen on the surfaces of the transparent yellow crystals .
Etymology and history
Althupit was discovered in 1985 in the "Kobokobo" pegmatites near Mwenga in the Lusungu River District in the Congolese province of Sud-Kivu . The first description was in 1987 by Paul Piret and Michel Deliens that the minerals by its chemical composition Al uminium, Th ORIUM, U ran and P hosphor well as the usual for minerals annex it named.
The type material , a few milligrams of the holotype of the mineral, is in the Royal Museum of Central Africa (English: Royal Museum of Central Africa ) in the Belgian municipality of Tervuren under the collection no. RMG 6.178 kept.
classification
Since the Althupite was only recognized as an independent mineral in 1986, it is not yet included in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . Only in the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this classic classification by Karl Hugo Strunz , the mineral received the system and mineral number. VII / E.07-130 (as of 2018). 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 Althupite together with arsenovan sea log , arsenuranylite , bergenite , dewindtite , dumontite , Francoisit- (Ce) , Francoisite- (Nd) , Hügelite , Kamitugait , Kivuit , Metavanmeer log , Mundite , Nielsbohrit , Phosphuranylit , Phuralumit , Phurcalit , Renardit , Vanmeer log and Yingjiangit form an independent but unnamed group.
The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also assigns Althupit to the class of "phosphates, arsenates and vanadates" and there in the department of "uranyl phosphates and arsenates" a. However, this is further subdivided according to the molar ratio of the uranyl complex to the phosphate, arsenate or vanadate complex, so that the mineral according to its composition can be found in the sub-section "UO 2 : RO 4 = 3: 2", where it is the only one Member forms the unnamed group 8.EC.25 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Althupit 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 April 42, 2013 within the sub-section “Water-containing phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 2 Z q × x (H 2 O)”.
Crystal structure
Althupite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a = 10.95 Å ; b = 18.57 Å; c = 13.50 Å; α = 72.6 °; β = 68.2 ° and γ = 84.2 ° as well as two formula units per unit cell .
| Crystal structure of Althupite |
|
| Color table: __ Al __ Th __ U __ P __ O |
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properties
The mineral is very radioactive due to its thorium content of up to 8.04% and its uranium content of up to 57.77% . Taking into account the proportions of the radioactive elements in the idealized empirical formula and the Folgezerfälle of the natural decay chains a specific activity of about 107.006 k for the mineral Bq stated / g (compared to natural potassium 0.0312 kBq / g). The quoted value can vary significantly depending on the mineral content and the composition of the levels; selective enrichment or depletion of the radioactive decay products is also possible and changes the activity.
Education and Locations
Althupite forms as a secondary mineral in the uranium-mineralized zones of granitic pegmatites , where it occurs mostly in association with beryl and columbite , but also with meta-autunite , mundite , phuralumite , ranunculite , threadgoldite , triangulite , upalite and other uranyl phosphates.
Apart from its type locality , the "Kobokobo" pegmatites from Sud-Kivu in the Democratic Republic of the Congo, no other location for Althupite is known (as of 2019). The "Kobokobo" pegmatites are characterized by a large mineral wealth, in which 14 minerals have been discovered for the first time. Apart from the abovementioned minerals mundite, Phuralumit, Ranunculit, Threadgoldit, Triangulit and Upalit are the still Eylettersit , Kamitugait , Kobokoboit , Metavanmeersscheit , Moreauit , Vanmeersscheit and Wakefieldit- (Ce) .
Precautions
Due to the radioactivity of the mineral, which is classified as very high , mineral samples should only be kept in dust- and radiation-tight containers, but above all 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
- Paul Piret, Michel Deliens: Les phosphates d'uranyle et d'aluminium de Kobokobo IX. L'althupite AlTh (UO 2 ) [(UO 2 ) 3 O (OH) (PO 4 ) 2 ] 2 (OH) 3 · 15H 2 O, nouveau mineral; properties and structures cristalline . In: Bulletin de Minéralogie . tape 110 , 1987, pp. 65–72 (French, available online at persee.fr [accessed October 10, 2019]).
- FC Hawthorne, EAJ Burke, TS Ercit, ES Grew, JD Grice, JL Jambor, J. Puziewicz, AC Roberts, DA Vanko: New mineral names . In: American Mineralogist . tape 73 , no. 1-2 , 1988, pp. 189–199 (English, minsocam.org [PDF; 1.6 MB ; accessed on October 10, 2019]).
Web links
- Mineral Atlas: Althupite (Wiki)
- American-Mineralogist-Crystal-Structure-Database - Althupite. In: rruff.geo.arizona.edu. Retrieved October 7, 2019 .
Individual evidence
- ↑ a b c 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 7, 2019 .
- ↑ a b c d e f g Stefan Weiss: The great 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 c d 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. 529 (English).
- ↑ a b c d e Althupite . 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; 68 kB ; accessed on October 7, 2019]).
- ^ A b c David Barthelmy: Althupite Mineral Data. In: webmineral.com. Retrieved October 7, 2019 .
- ↑ a b c d e Althupite. In: mindat.org. Hudson Institute of Mineralogy, accessed October 7, 2019 .
- ↑ a b List of localities for Althupite in the Mineralienatlas and Mindat
- ↑ Catalog of Type Mineral Specimens - A. (PDF 85 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed 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 7, 2019 .