Joosteit

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Joosteit
General and classification
other names
  • IMA 2005-013
  • Joosteite- mABC
chemical formula
  • Mn 2+ (Mn 3+ , Fe 3+ ) (PO 4 ) O
  • Mn 2+ Mn 3+ O (PO 4 )
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates
System no. to Strunz
and to Dana 		8.BB.15 ( 8th edition : VII / B.03)
06/41/03/06
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group I 2 / a (No. 15, position 3)Template: room group / 15.3
Lattice parameters a  = 11.888  Å ; b  = 6.409 Å; c  = 9.804 Å
β  = 106.17 °
Formula units Z  = 8
Twinning none observed
Physical Properties
Mohs hardness 4th
Density (g / cm 3 ) 4.13 (calculated)
Cleavage none observed
Break ; Tenacity not specified; brittle
colour black
Line color brownish black
transparency opaque, dark brown translucent only in the thinnest splinters
shine Semi-metallic luster

Joosteit is a very rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the chemical composition of Mn 2+ (Mn 3+ , Fe 3+ ) (PO 4 ) O and is therefore chemically seen a manganese - phosphate with an additional oxygen atom , ie a Oxophosphat.

At its type locality, Joosteit only develops irregularly formed aggregates up to several millimeters in size, which contain many inclusions of different sizes, which are residues of sicklerite and later alteration products such as hureaulite and various Fe / Mn oxides. The type locality of the mineral is the rare metal granite pegmatite Helikon II on the farm Okongava-Ost No. 72 near Karibib , constituency Karibib in the Erongo region , Namibia . In the past, the pegmatite was cultivated on petalite , amblygonite , pollucite , tantalite , beryl and lepidolite to produce the rare metals lithium , cesium , tantalum and beryllium .

Etymology and history

Joosteit was discovered by Paul Keller on a handpiece found on the dumps of the Helikon II pegmatite on the Okongava-Ost 72 farm near Karibib in Namibia during a research program on the occurrence, petrogenetic significance and structural characteristics of Staněkit . Paul Keller, Professor of Mineralogy and Crystallography at the University of Stuttgart , carried out the investigations necessary for characterization as a new mineral together with colleagues and presented the results to the International Mineralogical Association (IMA), which was published in 2005 under the provisional name IMA 2005- 013 recognized. In 2007 it was described by Paul Keller, François Fontan , Francisco Velasco Roldan and Philippe de Parseval in the German science magazine “New Yearbook for Mineralogy, Treatises” as Joosteit ( English Joosteite ). The authors named the mineral after Charlotte Jooste, Karibib / Namibia, in recognition of her outstanding support for pegmatite research in central Namibia. Jooste himself had worked on various pegmatites in the Karibib area for many years.

The type material for Joosteit (holotype) is kept at the University of Stuttgart (location TM-05.13-9911.07 / 0/824-s27 / 2). Further type material was deposited at the Muséum d'histoire naturelle de la ville de Toulouse , France , and in the Department de Mineralogia y Petrologia of the Universidad del País Vasco , Bilbao , Spain .

classification

The outdated, but partly still in use 8th edition of the mineral classification according to Strunz does not yet list the Joosteit. It would probably belong to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where together with Zwieselit , Wolfeit , Magniotriplit (discredited 2004), Sarkinit , Staněkit , Triplit , Triploidit and Wagnerit the "Zwieselit-Wolfeit-Gruppe" with the system no. VII / B.03 would have formed.

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Joosteit to the section of “Phosphates etc. with additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions to the phosphate, arsenate and vanadate complex, so that the mineral is classified in the sub-section “With only medium-sized cations; (OH etc.): RO 4  ≤ 1: 1 “can be found, where together with sarkinite, staněkite, triploidite, wagnerite and Wolfeit, the“ triploidite group ”with the system no. 8.BB.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Joosteit to the class of "phosphates, arsenates and vanadates" and there in the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here he is the sole namesake in the " Wolfeit Group " with the system no. 41.06.03 and the other members Wolfeit, Triploidit, Sarkinit and Staněkit can be found in the subsection "Anhydrous phosphates etc., with hydroxyl or halogen with (A) 2 (XO 4 ) Z q ".

Chemism

A total of 20 microprobe analyzes were carried out on various Joosteit grains from the "Helikon II pegmatite" . Analyzes on a relatively homogeneous grain with the highest Mn / Fe ratio resulted in mean values ​​of 0.22% Na 2 O; 0.43% MgO; 0.03% Al 2 O 3 ; 29.97% P 2 O 5 ; 0.15% K 2 O; 0.02% CaO; 31.14% MnO; 22.80% Mn 2 O 3 and 12.86% Fe 2 O 3 (MnO / Mn 2 O 3 ratio calculated from the stoichiometry). On the basis of five oxygen atoms , the empirical formula was calculated from them (Mn 2+ 1.004 Mg 0.024 Mn 3+ 0.660 Fe 3+ 0.368 Na 0.016 K 0.007 ) Σ = 2.079 (P 0.966 O 4 ) O, which leads to Mn 2+ 1 , 00 (Mn 3+ 0.64 Fe 3+ 0.36 ) Σ = 1.00 (PO 4 ) O was idealized. This ideal formula requires contents of 32.07% MnO, 22.84% Mn 2 O 3 , 13.00% Fe 2 O 3 and 32.09% P 2 O 5 (total 100.00% by weight).

Joosteit is the Mn 3+ -dominant analogue of the Fe 3+ -dominated Staněkit (more precisely Staněkit- Mabc ).

Crystal structure

Joosteit crystallizes in the monoclinic crystal system in the space group I 2 / a (space group no. 15, position 3) with the lattice parameters a  = 11.888  Å ; b  = 6.409 Å; c  = 9.804 Å and β = 106.17 ° and eight formula units per unit cellTemplate: room group / 15.3

The crystal structure of Joosteit consists - similar to that of Staněkit-Mabc - of two symmetrically different [MO 6 ] octahedra and a single [PO 4 ] tetrahedron , with those of Joosteit being more distorted than those of Staněkit. The [MO 6 ] octahedra have common edges and form zigzag chains that run parallel [010] for [(M1) O 6 ] and [100] for [(M2) O 6 ]. Both types of chains are linked by further edges along the c-axis and thereby form an open framework in which the isolated [PO 4 ] tetrahedra are located. Similar to the Staněkit-Mabc , the cations M 2+ and M 3+ (M = Mn and Fe) are distributed in both octahedral positions.

Another possibility to describe the topology of Joosteit is the reference to an oxygen-centered cation tetrahedron [OM 4 ], since the single central oxide anion O5 is not bound to any phosphorus atom. This [(O5) (M1) 2 (M2) 2 ] tetrahedron has trans-oriented edges and forms infinite cationic chains [(O5) (M1) 2/2 (M2) 2/2 ], which run parallel to the c- Axis extend. They are three-dimensionally linked to one another by discrete [PO 4 ] tetrahedra. From this point of view, Joosteit proves to be isotypic with the B-type structure of the lanthanoid (III) oxide oxosilicate Ln 2 [SiO 4 ] O and is closely related to other arrangements, which have analogous [OM 4/2 ] chains contain [OM4] tetrahedra linked by trans-oriented edges. These include a. In 2 [PO 4 ] O, Tb 2 [SeO 3 ] 2 O, Gd 3 OCl [AsO 3 ] 2, and La 3 OCl [AsO 3 ] 2 .

Joosteit is isotype (isostructural) to its Fe 3+ analogue Staněkit- Mabc . However, the crystal structures of Staněkit-Mabc and Joosteit differ significantly in their coordination numbers of cations and anions from the other representatives of the triplite and triploidite groups such as B. Wolfeit- Ma2bc , (Fe, Mn, Mg,) 2 [PO 4 ] (OH). For the latter minerals half of the cations are coordinated five or six times and the coordination number of the isolated anions (CN OH ) is only three, while in Joosteit all cations are six times coordinated and the single oxygen atom O5, which does not belong to any [PO 4 ] -Tetrahedron, has CN O5  = 4.

properties

morphology

At its type locality in the "Helikon-II-Pegmatit", Joosteit only develops aggregates of a few millimeters in size, whereby homogeneous grains are very rare and only reach sizes of 0.3 mm. Occasionally there are hints of elongated to latte crystals, but idiomorphic crystals are unknown. Twinning was also not observed.

physical and chemical properties

The aggregates of the Joosteits are black, their line color is always brownish- black . The surfaces of the opaque aggregates, which only show the thinnest shards of dark brown translucent aggregates, have a faint semi-metallic sheen . Under the microscope , the mineral is dark brown in transmitted light, gray with a brownish tinge in incident (reflected) light and has low to moderate bireflectance and a clear reflection pleochroism (weak in air, more pronounced in immersion oil). Internal reflexes were not observed.

No cleavage was found at the Joosteit . Although the mineral is clearly brittle, there is no information on breakage .

With a Mohs hardness of 4, the mineral is one of the medium-hard minerals and, like the reference mineral fluorite, can be easily scratched with a pocket knife. Due to the impurity of the type material, no density could be measured on the Joosteit ; the calculated density is 4.13 g / cm³. Joosteit is neither in the long term nor in the short wavelength UV light , a fluorescent .

Education and Locations

As of 2018, Joosteit could only be described as a very rare mineral formation from two sites. The type locality is the granite pegmatite Helikon II on the farm Okongava Ost 72 near Karibib, constituency Karibib in the Erongo region in Namibia. In addition, Joosteit was found in the "Pegmatyt Julianna" in the "Kopalnia DSS Piława Górna" quarry, Piława Górna (Ober-Peilau), Dzierżoniów District , Dolnośląskie , Poland . Occurrences of Joosteit in Germany , Austria or Switzerland are therefore not known.

Joosteit is a typical secondary mineral due to its type locality , which has formed in the oxidation zone of a granite pegmatite with primary phosphate mineral paragenesis. Similar to Staněkite and its relationship to triphyline and ferrisicklerite , Joosteit was created as a result of alteration processes at the expense of pegmatitic lithiophilite . In a first step, lithiophilite was typically converted into sicklerite. Later - under more strongly oxidising conditions - Joosteit was created by displacing the previously formed mineral. Joosteit is not an oxidation product of triploidite, (Mn, Fe) 2 (PO 4 ) (OH). Paragenesis minerals at the type locality are lithiophilite, sicklerite, eosphorite , amblygonite, varulite , dickinsonite , hureaulite , "apatite" and unidentified Fe / Mn oxides.

use

Naturally educated joosteit is extremely rare and therefore only of interest to mineral collectors. However, due to its chemical composition and its formation conditions in a lithium -containing mineral association, Joosteit may be considered for use in connection with lithium batteries . Due to the structural relationship to various polymorphs of the synthetic component Fe 2 [PO 4 ] O, catalytic and magnetic properties can also be expected.

See also

literature

  • Paul Keller, François Fontan, Francisco Velasco Roldan, Philippe de Parseval: Joosteite, Mn 2+ (Mn 3+ , Fe 3+ ) (PO 4 ) O: a new phosphate mineral from the Helikon II Mine, Karibib Namibia . In: New Yearbook for Mineralogy, Treatises . tape 183 , no. 2 , 2007, p. 197-201 , doi : 10.1127 / 0077-7757 / 2007/0069 .
  • Paul Keller, Falk Lissner, Thomas Schleid: The crystal structure of joosteite, (Mn 2+ , Mn 3+ , Fe 3+ ) 2 [PO 4 ] O, from the Helikon II mine, Karibib (Namibia), and its relationship to staněkite, (Fe 3+ , Mn 2+ , Fe 2+ , Mg) 2 [PO 4 ] O . In: New Yearbook for Mineralogy, Treatises . tape 184 , no. 2 , 2007, p. 225-230 , doi : 10.1127 / 0077-7757 / 2007/0095 .

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 aj ak al am an Paul Keller, François Fontan, Francisco Velasco Roldan , Philippe de Parseval: Joosteite, Mn 2+ (Mn 3+ , Fe 3+ ) (PO 4 ) O: a new phosphate mineral from the Helikon II Mine, Karibib Namibia . In: New Yearbook for Mineralogy, Treatises . tape 183 , no. 2 , 2007, p. 197-201 , doi : 10.1127 / 0077-7757 / 2007/0069 .
  2. ↑ Mindat - Joosteite (English)
  3. ^ IMA / CNMNC List of Mineral Names; March 2018 (PDF 1.65 MB)
  4. ↑ Typmineral catalog Germany - storage of the type material for Joosteit
  5. ↑ a b c d Paul Keller, Falk Lissner, Thomas Schleid: The crystal structure of joosteite, (Mn 2+ , Mn 3+ , Fe 3+ ) 2 [PO 4 ] O, from the Helikon II mine, Karibib (Namibia) , and its relationship to staněkite, (Fe 3+ , Mn 2+ , Fe 2+ , Mg) 2 [PO 4 ] O . In: New Yearbook for Mineralogy, Treatises . tape 184 , no. 2 , 2007, p. 225-230 , doi : 10.1127 / 0077-7757 / 2007/0095 .
  6. ↑ Mindat - Number of locations for Joosteit
  7. ↑ a b List of locations for Joosteit in the Mineralienatlas and in Mindat
  8. ↑ Adam Pieczka, Adam Włodek, Bożena Gołębiowska, Eligiusz Szełęg, Adam Szuszkiewicz, Sławomir Ilnicki, Krzysztof Nejbert, Krzysztof Turniak: Phosphate-bearing pegmatites in the Góry Sowie Block and adjacent areas, Sudetes, SW Poland . In: Book of Abstracts 7th International Symposium on Granitic Pegmatites . PEG 2015 Książ, Poland. 2015, p. 77–78 (English, researchgate.net [PDF; 357 kB ; accessed on August 11, 2018]).
  9. ↑ Diana Twardak, Adam Pieczka: Phosphates in the Julianna pegmatitic system at Piława Górna, Góry Sowie block . In: Martin Ondrejka, Jan Cempírek, Peter Bačík (Eds.): Book of Contributions and Abstracts Joint 5th Central European Mineralogical Conference and 7th Mineral Sciences in the Carpathians Conference . Banská Štiavnica June 26–30, 2018. Mineralogical Society of Slovakia, Comenius University Bratislava 2018, ISBN 978-80-223-4548-4 , p. 108 (English, cemc2018.com [PDF; 17.4 MB ; accessed on August 11, 2018]).