Khanneshit

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Khanneshit
General and classification
other names

IMA 1981-025

chemical formula
  • (NaCa) 3 (Ba, Sr, TR, Ca) 3 (CO 3 ) 5
  • (Na, Ca) 3 (Ba, Sr, REE, Ca) 3 [CO 3 ] 5
  • (Na, Ca) 3 (Ba, Sr, Ce, Ca) 3 (CO 3 ) 5
  • (Na 2.75 Ca 0.23 ) 2.98 (Ba 1.08 Sr 0.63 Ca 0.46 Ce 0.46 -La 0.18 Nd 0.15 Pr 0.04 ) 3.00 · (CO 3 ) 5
  • (Na, Ca) 3 (Ba, Sr, Ce, Ca) 3 (CO 3 ) 5
Mineral class
(and possibly department) 		Carbonates and nitrates - carbonates without additional anions; without H 2 O
System no. to Strunz
and to Dana 		5.AC.30 ( 8th edition : V / B.07-050 according to Lapis classification)
04/14/04/02
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  = 10.5790  Å ; c  = 6.5446 Å
Formula units Z  = 2
Physical Properties
Mohs hardness "soft"; 3 to 4
Density (g / cm 3 ) 3.8 to 3.9 (measured); 3.94 (calculated)
Cleavage imperfectly parallel to the longitudinal extension
Break ; Tenacity not specified; fragile to brittle
colour light yellowish, almost colorless
Line color White
transparency semi-transparent; transparent
shine Glass gloss
radioactivity weakly radioactive
Crystal optics
Refractive indices n ω  = 1.620 to 1.623
n ε  = 1.608 to 1.610
Birefringence δ = 0.012 to 0.013
Optical character uniaxial negative
Other properties
Chemical behavior easily soluble in HCl

Khanneshite is a rarely occurring mineral from the mineral class of " carbonates and nitrates " (formerly carbonates, nitrates and borates ). It crystallizes in the hexagonal crystal system with the idealized chemical composition (Na, Ca) 3 (Ba, Sr, Ce, Ca) 3 (CO 3 ) 5 - so from a chemical point of view it is a sodium - barium - carbonate with a more or less high content of strontium , Calcium and SEE . Due to the cerium content , the mineral can be radioactive .

Khanneshite forms elongated, prismatic crystals up to 1 cm in length and 3 mm in diameter as well as radially fibrous or fine-grained aggregates , which are often altered and displaced by barite .

The type locality of the Khanneshit is a uranium and REE deposit in the central part of the early Quaternary carbonatite extending over an area of ​​40 km² in the "Khanneshin Complex" ( coordinates of the Khanneshin Complex ), Dushan District (Chanashin District?), Province Helmand , Afghanistan .

Etymology and history

In 1974 Geliy Kuzmich Eremenko identified an unknown mineral from the Burbankite group in samples from the Khanneshin carbonatite complex in Afghanistan, which contained an unusually high amount of barium and which proved to be a new phase in further investigations. After determining the necessary crystallographic, physical and chemical-crystal chemical properties, the mineral was submitted to the International Mineralogical Association (IMA), which recognized it as a new mineral on June 27, 1981 under the provisional designation "IMA 1981-025".

In 1982 the first scientific description of this mineral was made by a team of Soviet scientists with Geliy Kuzmich Eremenko and VA Vel'ko in the Soviet science magazine "Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva" ("Proceedings of the Soviet Mineralogical Society") as Khanneshite ( English Khanneshite , Russian Ханенен ). They named the mineral after its type locality, the Khanneshin carbonatite complex in Afghanistan.

The type material for khanneshit is kept in the systematic collection of the Mineralogical Museum " Alexander Evgenjewitsch Fersman " of the Russian Academy of Sciences in Moscow . Other type material was deposited in the collection of the Museum of the State Mining University in Saint Petersburg . The catalog numbers of the mineral grades forming the type material are not known.

classification

Since the khanneshite was only recognized as an independent mineral by the IMA in 1981 and the discovery was only published in 1982, it is not listed in the 8th edition of the Strunz mineral classification, which has been out of date since 1977 . There it would have belonged to the common mineral class of "carbonates, nitrates and borates" and there to the department of "carbonates", where together with Burbankit , Bütschliit , Carbocernait , Eitelite , Fairchildite , Nyerereit , Sahamalith and Shortit, it formed the "Eitelite Sahamalith group" “With the system no. Vb / A.05 within the sub-section “Anhydrous carbonates without foreign anions ”.

In the Lapis mineral directory , which was last revised and updated in 2018 , which is still based on the outdated system of Karl Hugo Strunz out of consideration for private collectors and institutional collections , the mineral was given the system and mineral number. V / B.07-050 . In the "Lapis system" this corresponds to the section "Anhydrous carbonates [CO 3 ] 2− , without foreign anions ", where khanneshite together with Rémondite (La) , Rémondite (Ce) , Petersenite (Ce) , Calcioburbankite , Burbankit, Sanrománit and Carbocernait the Burbankit series with system no. V / B.07 forms.

The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the IMA until 2009, assigns the khanneshite to the class of “carbonates and nitrates”, which has been reduced by the borates, and there to the category of “carbonates without additional anions; without H 2 O “. This is, however, further subdivided according to the predominant group of elements in the compound (alkali and / or alkaline earth metals), so that the mineral can be found according to its composition in the subsection " Alkali and alkaline earth carbonates", where it can be found together with burbankite, calcioburbankite and Sanrománit the "Burbankit group" with the system no. 5.AC.30 forms.

Also the systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Khanneshit like the outdated Strunz'sche systematics to the common class of "carbonates, nitrates and borates" and there in the department of "anhydrous carbonates". Here it is together with Burbankit, Calcioburbankit and Sanrománit in the " Burbankitgruppe (Hexagonal) " with the system no. 04/14/04 within the sub-section "Anhydrous carbonates with a compound formula A 2+ B 2+ 2 (CO 3 ) 4 ".

Chemism

Two analyzes on the type material showed 38.85% and 38.30% BaO; 5.80% and 6.50% SrO; 6.13% and 7.30% CaO, respectively; 0.08% and 0.07% MnO; 6.99% and 6.55% Na 2 O, respectively ; 0.77% and 0.60% K 2 O, respectively ; 0.13% and 0.25% Fe 2 O 3 , respectively ; 0.26% and 0.12% Al 2 O 3 , respectively ; 0.39% and 0.70% SiO 2 , respectively ; 8.43% and 8.71% SEE 2 O 3 , respectively ; 24.56% and 22.66% CO 2 , respectively ; 4.91% and 6.98% SO 3 , respectively ; 1.46% or 1.30% H 2 O + ; 0.07% and 0.0% H 2 O - ; Sum 99.98% or 100.87%. After the detection of barite , chlorite and dolomite and the recalculation to 100%, the empirical formulas (Na 2.13 Ca 0.87 ) Σ = 3.00 (Ba 1.82 Sr 0 ) were calculated on the basis of 15 oxygen atoms , 53 SEE 0.49 K 0.15 ) Σ = 2.99 C 4.96 O 15 · 0.67H 2 O and (Na 2.02 Ca 0.98 ) Σ = 3.00 (Ba 1.55 Sr 0.60 SEE 0.51 Ca 0.25 K 0.12 ) Σ = 3.03 C 4.89 O 15 · 0.55H 2 O

Although values ​​for water are given in some analyzes of minerals of the Burbankit Group, the formulas of these minerals do not contain water. Minerals of the Burbankit group are unstable, often altered and hydrated - which explains the water content. If the water is not taken into account, the empirical formulas for Khanneshit can be idealized to (Na, Ca) 3 (Ba, Sr, SEE, Ca) 3 (CO 3 ) 5 with Na> Ca, Ba> Sr, Ca, SEE. The composition of the rare earth elements in the two samples of the Khanneshite from the type locality was determined spectroscopically and shows a clear predominance of cerium in both analyzes, as is almost always the case with the minerals of the Burbankite group:

  • La 20.3 Ce 44.0 Pr 6.0 Nd 9.5 Sm 6.0 Eu 0.1 Gd 4.8 Dy 0.3 Ho 0.2 Er 0.8 Tm 0.05 Yb 0.5 Y 7 , 5 or
  • La 20.9 Ce 51.2 Pr 4.7 Nd 7.3 Sm 4.7 Eu 0.1 Gd 3.7 Dy 0.4 Ho 0.1 Er 0.9 Tm 0.56 Yb 0.2 Y 5 ,8th

A microprobe analysis of a Khanneshits from the Khibiny Mountains , which was used for crystal structure refinement, yielded 22.99% BaO; 9.04% SrO; 5.37% CaO; 11.86% Na 2 O; 0.0% K 2 O; 4.07% La 2 O 3 ; 10.46% Ce 2 O 3 ; 1.01% Pr 2 O 3 ; 3.60% Nd 2 O 3 and 30.59% CO 2 (total 98.99%). This corresponds to an empirical formula of (Na 2.75 Ca 0.23 ) Σ = 2.98 (Ba 1.08 Sr 0.63 Ca 0.46 Ce 0.46 La 0.18 Nd 0.15 Pr 0.04 ) Σ = 3.00 (CO 3 ) 5.00

The official formula of the IMA for the khanneshite is given as (Na, Ca) 3 (Ba, Sr, Ce, Ca) 3 (CO 3 ) 5 . The Strunz formula is (Na, Ca) 3 (Ba, Sr, REE, Ca) 3 [CO 3 ] 5 . As usual, the anion group is summarized here in square brackets; In addition, not only the most common SEE is given, but all SEE are subsumed under “REE”.

The only combination of elements Na – Ca – Sr – Ba – Ce – C – O, as can be found in the IMA's official formula for khanneshite, among the currently known minerals (as of 2020), apart from khanneshite, only burbankite (Na, Ca ) 3 (Sr, Ba, Ce) 3 (CO 3 ) 5 , Carbocernaite , (Ca, Na) 3 (Sr, Ce, Ba) 3 (CO 3 ) 5 , and the unnamed phase UM1990-98-CO: BaCaNaREESr , (Na, Ca) 3 (Sr, Ba, Ce) 3 (CO 3 ) 5 .

Khanneshite can be understood as the Ba-dominant analogue of the Sr-dominated Burbankite, with strontium dominating among the cations on the B position in the latter .

From a chemical point of view, like burbankite, calcioburbankite, remondite (Ce), remondite (La) and petersenite (Ce), khanneshite belongs to the burbankite group, which is a group of six minerals with the general formula А 3 В 3 (СО 3 ) 5 and А = Na > Ca , SEE 3+ or a vacancy (◻) as well as B = Sr , Ca, Ba , SEE 3+ and / or Na. All representatives of this Burbankit group investigated by Julia Belovitskaya and Igor Pekov (94 analyzes) can be used in an isomorphic system with the - hypothetical - end members (Na 2 Ca) М 2+ 3 (CO 3 ) 5 and Na 3 (SEE 2 Na) (CO 3 ) 5 , with М 2+  = Sr, Ba and / or Ca, can be described.

Crystal structure

The current investigation on the crystal structure of the khanneshite according to the official IMA list comes from Igor Pekov and colleagues; Julia Belovitskaya and colleagues presented a more recent determination of the crystal structure of the khanneshite using the Rietveld method . According to the latter investigation, khanneshite crystallizes in the hexagonal crystal system in the space group P 6 3 mc (space group no. 186) with the lattice parameters a = 10.5790  Å and c = 6.5446 Å as well as two formula units per unit cell . Template: room group / 186

As with all representatives of the Burbankit group, eight-coordinate polyhedra with common faces (in this case (Na, Ca) [8] polyhedra) form chains in the direction of the c-axis [0001] in the crystal structure of the khanneshite . The chains are linked by ten-coordinate polyhedra (in this case (Ba, Sr, Ce, Ca) [10] polyhedra) and CO 3 groups. Two of the five CO 3 groups are in the (0001) plane, the other three are inclined. In detail, one can imagine that - similar to the burbankite - in the crystal structure of the calcioburbankite there are two independent and ordered cation positions in the centers of polyhedra with eight or ten vertices ( A and B ), which are Atoms and three types of carbonate groups labeled C (1), C (2) and C (3) with different orientations are formed.

Khanneshit, Burbankit and Calcioburbankit are isotypic (isostructural).

properties

morphology

At the type locality, khanneshite forms elongated, prismatic crystals up to 1 cm in length and 3 mm in diameter as well as radially fibrous or fine-grained aggregates, which are often altered and displaced by powdery barite.

physical and chemical properties

The crystals of the khanneshit of the type locality are light yellowish to almost colorless, while their stroke color is indicated as white. The surfaces of the semi-transparent or transparent crystals of the Khanneshit show a characteristic glass-like sheen . In accordance with this glass gloss, khanneshite has high light refraction ( n ε  = 1.608 to 1.610; n ω  = 1.620 to 1.623) and low birefringence (δ = 0.012 to 0.013). In transmitted light, the uniaxial negative khanneshit is colorless and obviously does not show any pleochroism .

Khanneshite has an imperfect cleavage parallel to the longitudinal extension of the crystals. The mineral is brittle or fragile, there is no information about its breakage . Khanneshite is "soft", has a Mohs hardness of 3 to 4 and is therefore one of the medium-hard minerals that, like the reference minerals calcite (hardness 3), can be easily scratched with a copper coin and fluorite (hardness 4) with a pocket knife. The measured density for khanneshite is 3.8 to 3.9 g / cm³, the calculated density is 3.94 g / cm³.

The mineral is neither (356 nm) (nm 254) in the long wavelength even in the short wavelength light UV a fluorescence . Khanneshite is easily soluble in hydrochloric acid , HCl.

Education and Locations

Khanneshite is a late-formed mineral and was found at its type locality finely distributed in hydrothermally converted fine-grain dolomite and dolomite-anchorite carbonatites . Further findings come from a core sample from a narrow carbonatite transition in a differentiated alkaline rock massif (Khibiny Mountains, Kola, Russia), of calcite amphibole - clinopyroxene -Gesteinen (Afrikanda) and calcite Shortite -Karbonatiten (kovdor).

Minerals accompanying the khanneshite at its type locality are dolomite , calcinsite (Ce) , carbocernaite , mckelveyite , barite and a mineral of the chlorite group , while it is accompanied in the chibines by calcite, dawsonite and magnetite . In Kowdor, phlogopite and bonshtedtite belong to the paragenesis of khanneshit.

As a very rare mineral formation, khanneshite (as of 2020) is only known from eight other sites in addition to its type locality. The type locality of the Khanneshit is a uranium and REE deposit in the central part of the early Quaternary carbonatite, which extends over an area of ​​40 km², in the "Khanneshin Complex", Dushan District (Chanashin District?), Helmand Province , Afghanistan .

Other locations for khanneshit are:>

Locations for khanneshite from Germany , Austria and Switzerland are therefore unknown.

use

Due to its rarity, khanneshite has no commercial significance and is only of interest to mineral collectors.

Precautions

Khanneshite is classified as weakly radioactive due to its content of rare earth elements and radioactive isotopes of the REE cerium and lanthanum and has a specific activity of about 154  Bq / g (for comparison: natural potassium 30.346 Bq / g). In spite of the only weak radioactivity of the mineral, mineral samples from Khanneshit should only be kept in dust- and radiation-proof 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 respiratory protection mask and gloves should be worn when handling the mineral .

See also

literature

  • Geliy Kuzmich Eremenko, VA Vel'ko: Ханнешит (Na, Ca) 3 (Ba, Sr, TR, Ca) 3 (CO 3 ) 5 - новый минерал группы Бербанкита (Khanneshite, (Na, Ca) 3 (Ba, Sr, RE, Ca) 3 (CO 3 ) 5 , a new mineral from the burbankite group) . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 111 , no. 3 , 1982, pp. 321–324 (Russian, rruff.info [PDF; 268 kB ; accessed on March 4, 2020]).
  • Khanneshite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 66 kB ; accessed on March 4, 2020]).

Web links

Individual evidence

  1. ↑ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai Geliy Kuzmich Eremenko, VA Vel'ko: Ханнешит (Na, Ca ) 3 (Ba, Sr, TR, Ca) 3 (CO 3 ) 5 - новый минерал группы Бербанкита (Khanneshite, (Na, Ca) 3 (Ba, Sr, RE, Ca) 3 (CO 3 ) 5 , a new mineral of the burbankite group) . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 111 , no. 3 , 1982, pp. 321–324 (Russian, rruff.info [PDF; 268 kB ; accessed on March 4, 2020]).
  2. ↑ a b c d 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.  291 (English).
  3. ↑ a b c d e f Khanneshite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 66  kB ; accessed on March 4, 2020]).
  4. ↑ a b c d e f g Yulia V. Belovitskaya, Igor V. Pekov, Elena R. Gobechiya, Y. K Kabalov, J. Schneider: Determination of the crystal structure of khanneshite by the Rietveld method . In: Crystallography Reports . tape 47 , no. 1 , 2002, p. 39-42 , doi : 10.1134 / 1.1446907 (English).
  5. ↑ 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; 1762 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, January 2020, accessed January 20, 2020 .
  6. ↑ a b c d e f Khanneshit. In: mindat.org. Hudson Institute of Mineralogy, accessed March 4, 2020 .
  7. ↑ a b c d e f g h i j David Barthelmy: Khanneshite Mineral Data. In: webmineral.com. Retrieved March 4, 2020 .
  8. ↑ Catalog of Type Mineral Specimens - K. (PDF 96 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed March 4, 2020 .
  9. ↑ 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 .
  10. ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed September 25, 2019 .
  11. ↑ Minerals with Na-Ca-Sr-Ba-Ce-C-O. In: mindat.org. Hudson Institute of Mineralogy, accessed March 4, 2020 .
  12. ↑ a b c d e Yulia V. Belovitskaya, Igor V. Pekov: Genetic mineralogy of the burbankite group . In: Genetic mineralogy of the burbankite group . tape 39 , 2004, p. 50-64 ( rruff.info [PDF; 1.1 MB ; accessed on October 4, 2019]).
  13. ↑ Igor V. Pekov, Nikita V. Chukanov, Yulia V. Belovitskaya: Ханнешит и Петерсенит из Хибин (Khanneshite and petersenite- (Ce) from Khibiny) . In: Zapiski Vserossiyskogo Mineralogicheskogo Obshchestva . tape 127 , no. 2 , 1998, p. 92-100 (Russian).
  14. ↑ Localities for Khanneshite. In: mindat.org. Hudson Institute of Mineralogy, accessed March 4, 2020 .
  15. ↑ a b c List of locations for khanneshite in the Mineralienatlas and Mindat (accessed on March 3, 2020)