Abellaite

from Wikipedia, the free encyclopedia
Abellaite
Abellaite-738453.jpg
Group with white, mica-like abellaite crystals (field of view 1.62 mm)
General and classification
other names

IMA 2014-111

chemical formula
  • NaPb 2 (CO 3 ) 2 (OH)
  • NaPb 2 [OH | (CO 3 ) 2 ]
Mineral class
(and possibly department) 		Carbonates and nitrates
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol dihexagonal-pyramidal; 6 mm
Space group P 6 3 mc (No. 186)Template: room group / 186
Lattice parameters a  = 5.254 (2)  Å ; c  = 13.450 (5) Å
Formula units Z  = 2
Physical Properties
Mohs hardness "soft"
Density (g / cm 3 ) calculated: 5.93
Cleavage not observed
Break ; Tenacity not specified, friable
colour colorless, white
Line color White
transparency translucent
shine Glass gloss, pearlescent gloss
Other properties
Chemical behavior insoluble in water, dissolving in 20% HCl at room temperature

Abellaite is a very rarely occurring mineral from the mineral class of "carbonates and nitrates" with the chemical composition NaPb 2 (CO 3 ) 2 (OH) and therefore, chemically speaking, sodium - lead - carbonate with additional hydroxide ions .

Abellaite crystallizes in the hexagonal crystal system , but has so far only been observed in the form of microscopic crystals and aggregates with a size between 10 μm and ≈ 30 μm. The mineral is usually colorless and transparent, but due to multiple refraction due to its polycrystalline formation , it appears translucent white with a glass- to mother-of-pearl-like sheen on the surfaces.

Etymology and history

The mineral in the former was discovered copper and - Uranium - mine Eureka at Torre de Cabdella in the Catalan province of Lleida in Spain , where it is as thin crusts on primary minerals found.

After recognition as an independent mineral by the International Mineralogical Association (IMA) in 2014, it was officially first described in 2017 by Jordi Ibáñez-Insa, José J. Elvira, Xavier Llovet, Jordi Pérez-Cano, Núria Oriols, Martí Busquets-Masó and Sergi Hernández. They named the abellaite in honor of the Catalan gemologist Joan Abella i Creus (* 1968), who had been investigating the mineralization of the Mina Eureka for a long time and who also found the mineral named after him.

classification

Since the abellaite was only recognized as an independent mineral in 2014, it is not yet listed in the 8th edition of the mineral classification according to Strunz , which has been outdated since 1977 . The 9th edition of Strunz's mineral systematics, which has been valid since 2001 and was updated by the IMA until 2009, therefore does not list the abellaite. The same applies to the Dana system of minerals, which is mainly used in the English-speaking world .

Only in the last revised and updated Lapis mineral directory according to Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is based on the old form of the systematics by Karl Hugo Strunz in the 8th edition, the mineral received the system and mineral No. V / C.08-30 . In the "lapis system" this corresponds to the class of "nitrates, carbonates and borates" and there the department " anhydrous carbonates, with foreign anions ", where abellaite together with hydrocerussite , plumbonacrite and shannonite forms an independent but unnamed group (status no 2018).

Chemism

The mean values ​​from 10 microprobe analyzes resulted in a chemical composition of 3.88% sodium (Na), 0.29% calcium (Ca), 72.03% lead (Pb), 4.17% carbon (C), 19.47% Oxygen (O) and 0.17% hydrogen (H) (H, C and O were determined stoichiometrically assuming the ideal formula).

The empirical formula Na 0.96 Ca 0.04 Pb 1.98 (CO 3 ) 2 (OH) was determined on the basis of seven oxygen atoms and simplified to the idealized formula NaPb 2 (CO 3 ) 2 (OH).

Crystal structure

Abellaite crystallizes hexagonally in the space group P 6 3 mc (space group  no.186 ) with the lattice parameters a = 5.254 (2)  Å and c  = 13.450 (5) Å as well as two formula units per unit cell . Template: room group / 186

Education and Locations

Abellaite is found as thin crusts on the surface of primary minerals . It develops weakly formed crystals with a size of no more than 10 µm as well as larger pseudo-hexagonal platelets with a size of up to 30 µm. Individual crystals are usually tabular or lamellar and come together to form disordered aggregates . As Begleitminerale contact a plurality of primary minerals such as, inter alia, chalcopyrite , nickel cobaltite , Coffinit , covellite , galena , pyrite , roscoelite , sphalerite , tennantite and uraninite and (secondary) as supergene minerals Andersonite , aragonite , Čejkait , Devillin , Gordait , hydrozincite , malachite and arsenic-rich vanadinite .

Abellaite is one of the very rare mineral formations, only a few samples of it have been found so far. Apart from its type of locality , the Eureka mine in the Catalan province of Lleida (Spain), the mineral was only able to be found in the so-called "Jubilee" pegmatite dike (Russian Юбилейная ; English transcription Yubileinaya , German transcription Jubilejnaja ) on the Karnassurt mountain in the Lowosero massif ( Lowosero Tundra ) on the Russian Kola Peninsula .

See also

literature

  • EL Belokoneva, AG Al'-Ama, OV Dimitrova, VS Kurazhkovskaya, SY Stefanovich: Synthesis and crystal structure of new carbonate NaPb 2 (CO 3 ) 2 (OH) . In: Crystallography Reports . tape 47 , 2002, p. 217–222 (English, rruff.info [PDF; 83 kB ; accessed on February 11, 2020]).
  • Ulf Hålenius, Frédéric Hatert, Marco Pasero, Stuart J. Mills: IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 29. New minerals and nomenclature modifications approved in 2015 and 2016 . In: Mineralogical Magazine . tape 80 , 2016, p. 199–205 , doi : 10.1180 / minmag.2016.080.080 (English, rruff.info [PDF; 94 kB ; accessed on February 11, 2020]).
  • Jordi Ibáñez-Insa, José J. Elvira, Xavier Llovet, Jordi Pérez-Cano, Núria Oriols, Martí Busquets-Masó, Sergi Hernández: Abellaite, NaPb 2 (CO 3 ) 2 (OH), a new supergene mineral from the Eureka mine , Lleida province, Catalonia, Spain . In: European Journal of Mineralogy . tape 29 , 2017, p. 915–922 , doi : 10.1127 / ejm / 2017 / 0029-2630 (English, available online at researchgate.net [accessed February 11, 2020]).

Web links

Commons : Abellaite  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: January 2020. (PDF 1729 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, January 2020, accessed February 20, 2020 .
  2. ↑ 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 .
  3. ↑ a b c d e f g h i j k l m n Jordi Ibáñez-Insa, José J. Elvira, Xavier Llovet, Jordi Pérez-Cano, Núria Oriols, Martí Busquets-Masó, Sergi Hernández: Abellaite, NaPb 2 (CO 3 ) 2 (OH), a new supergene mineral from the Eureka mine, Lleida province, Catalonia, Spain . In: European Journal of Mineralogy . tape 29 , 2017, p. 915–922 , doi : 10.1127 / ejm / 2017 / 0029-2630 (English, available online at researchgate.net [accessed February 20, 2020]).
  4. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed February 20, 2020 .
  5. ↑ List of locations for abellaite in the Mineralienatlas and Mindat , accessed on February 20, 2020.