Ludjibait

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Ludjibait
Ludjibaite-99355.jpg
Bluish-green spherical aggregates and crusts of ludjibaite from the Podlipa and Reinera mines, Ľubietová, western part of Slovenské Rudohorie Mts, Banská Bystrica region, Slovakia Image width 4 mm.
General and classification
chemical formula Cu 5 [(OH) 4 | (PO 4 ) 2 ]
Mineral class
(and possibly department) 		Phosphates, arsenates and vanadates
System no. to Strunz
and to Dana 		8.BD.05. ( 8th edition : VII / B.11-10)
41.4.3.3
Similar minerals Malachite (name!), Cornwallite, Libethenite
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Space group P 1 (No. 2)Template: room group / 2
Lattice parameters a  = 4.446  Å ; b  = 5.871 Å; c  = 8.680 Å
α  = 103.9 °; β  = 90.3 °; γ  = 93.2 °
Formula units Z  = 1
Twinning after (01 1 )
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) 4.36 (calculated)
Cleavage not defined
Break ; Tenacity uneven; Tenacity not defined
colour dark blue-green
Line color pale blue to white
transparency translucent to opaque
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.786
n β  = not defined
n γ  = 1.840
Birefringence δ = 0.054
Optical character biaxial negative or positive
Axis angle 2V = large
Pleochroism faint from azure to pale blue hues

Ludjibaite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the triclinic crystal system with the composition Cu 5 [(OH) 4 | (PO 4 ) 2 ], so from a chemical point of view it is a copper phosphate with additional hydroxide ions .

Ludjibaite occurs in the form of comb-shaped mineral aggregates , which are built up from lanceolate-shaped, leafy-thin tabular crystals up to 0.3 mm in size according to (01 1 ) . Characteristically, they show dark bluish-green hues.

Etymology and history

Bluish green ludjibaite crystals on quartz from the type locality, the Ludjiba deposit in the Democratic Republic of the Congo (size: 3.6 cm × 1.6 cm × 1.2 cm)

Ludjibait was first discovered in the province of Haut-Katanga in the Democratic Republic of the Congo , more precisely in the Ludjiba deposit on the river of the same name and the mountains of the same name not far from Shinkolobwe , and was first described in 1988 by the Belgian crystallographer Paul Piret and the Belgian mineralogist Michel Deliens. They named the mineral Ludjiba after its type locality.

Type material of the mineral is on the one hand kept in the Royal Museum for Central Africa in Tervuren , Belgium (catalog no. RMG 14.445), where it occurs together with pseudomalachite and libethenite on the same level. Another sample is kept in the Museum of Natural Sciences in Brussels (catalog no. RC 3.514).

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the ludjibaite belonged to the division of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where it was used together with arsenoclasite , cornubite , cornwallite , gatehouseit , pseudomalachite , Reichenbachit , Reppiait and Turanit form the unnamed group VII / B.11 .

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 ludjibaite to the category 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 or vanadate complex (RO 4 ), so that the mineral is classified in the sub-section “With only medium-sized cations; (OH etc.): RO 4  = 2: 1 "can be found where - without further representatives - the" Ludjibaitgruppe "with the system no. 8.BD.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns ludjibaite to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates, etc., with hydroxyl or halogen". Here it can be found together with pseudomalachite and Reichenbachite in the unnamed group 41.04.03 within the subsection " Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 2 Z q ".

Crystal structure

Ludjibaite crystallizes in the triclinic crystal system in the space group P 1 (space group no. 2) with the lattice parameters a  = 4.446  Å ; b  = 5.871 Å; c  = 8.680 Å; α = 103.9 °; β = 90.3 ° and γ = 93.2 ° and one formula unit per unit cell . Template: room group / 2

The crystal structure consists of four crystallographically singular copper atoms, which are located in characteristically deformed (four short and two long bonds), 6-fold coordinated positions. They are linked to one another and thereby form two-dimensional, copper-containing layers. As with the two polymorphs of Ludjibait, these layers (which are connected to one another by phosphate tetrahedra and hydrogen bonds) can be derived from a two-dimensional framework of copper-containing polyhedra with common edges.

properties

morphology

Ludjibaite mostly occurs in the form of comb-shaped, spherical-kidney-grape-like aggregates with a concentric-radial-fiber structure. Sometimes these aggregates are built up from lanceolate, leaf-like crystals up to 0.3 mm in size according to (01 1 ). Occasionally there are discrete zones in massive, monomineral-looking pseudomalachite aggregates of Ľubietová alternating from ludjibaite, rich bachite and pseudomalachite - all three Cu 5 (PO 4 ) 2 (OH) 4 polymorphs occur in one and the same spherical aggregate. Spherical aggregates up to 6 mm in size from the "Käusersteimel Pit" consist of pseudomalachite on the inside, while the outer part is made up of a mixture of Ludjibaite and Reichenbachite. The proportion of Reichenbachite increases steadily towards the surface of the spherical aggregates, so that the sequence of deposition can be specified as Pseudomalachite → Ludjibaite → Reichenbachite.

physical and chemical properties

The color of the Ludjibaite is dark bluish green, its line color varies from pale blue to white. While the aggregates are silky glossy, the translucent to opaque crystals have a glass gloss. The Mohs hardness of Ludjibaite is unknown. The chemical behavior of ludjibaite is not described, but the mineral should dissolve in acids and NH 4 (OH) just as well as its polymorph pseudomalachite.

Modifications and varieties

The compound Cu 5 [(OH) 4 | (PO 4 ) 2 ] is trimorphic and occurs naturally in addition to the triclinic crystallizing Ludjibaite as monoclinic crystallizing pseudomalachite and Reichenbachite .

Education and Locations

Ludjibaite forms secondarily in the oxidation zone of copper deposits . Other copper phosphates or arsenates can occur as accompanying minerals . At the type locality, the mineral crystallizes on pseudomalachite and is accompanied by libethenite. At the ubietová (Libethen) sites near Banská Bystrica (Neusohl) and “Grube Käusersteinel” near Kausen, all three polymorphs of Cu 5 (PO 4 ) 2 (OH) 4 , i.e. ludjibaite, rich bachite and pseudomalachite, occur. The socialization with pseudomalachite is typical for many sites. When Ludjibaite was first found in Ľubietová, both Ludjibaite and Reichenbachite were identified on the same level - but in different cavities.

As a rare mineral formation, Ludjibaite could only be proven at a few sites. So far (as of 2016) around 10 sites are known. In addition to its type locality , the "Ludjiba" deposit in the province of Haut-Katanga , 12 km southwest of Kambove and 20 km west of Likasi , the mineral also occurred in the "Shituru Mine" near Likasi, Province in the Democratic Republic of the Congo (Zaïre) Skin katanga, on. The most important European site is the "Reiner-Stollen", Podlipa near beiubietová (Libethen) not far from Banská Bystrica (Neusohl), Slovakia . In Germany the mineral was found in the "Käusersteimel" mine near Kausen and in the "Kalterborn" mine in Eisenzecher Zug near Siegen , both in Siegerland . In Austria , Ludjibait has so far only been found in the Tanzer quarry near Falkenstein in the Fischbacher Alps , Styria . Locations in Switzerland are not known.

Other sites are Jáchymov (St Joachimsthal), Jáchymov District (St Joachimsthal), Krušné Hory , Karlovy Vary Region , Bohemia , Czech Republic ; the Christiana Mine near Agios Konstantinos , Lavrion , Attikí , Greece , the Mina Manto Cuba, San Pedro de Cachiyuyo District, Inca de Oro, Chañaral Province, Atacama Region , Chile . For Namibia , the mineral from the "Old Bobos Mine" on the farm Uris 481 at was Otavi region Otjozondjupa , and from 25km north of Rosh Pinah lying "Skorpion Zinc Mine", Region ǁKaras Region described.

See also

literature

  • P. Piret, M. Deliens (1988): Description de la ludjibaite, un polymorphic de la pseudomalachite, Cu 5 (PO 4 ) 2 (OH) 4 , In: Bulletin de Minéralogie. , Vol. 111, pp. 167-171.

Web links

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

Individual evidence

  1. ↑ 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 .
  2. ↑ a b c d e f g h i j k l m P. Piret, M. Deliens (1988): Description de la ludjibaite, un polymorphic de la pseudomalachite, Cu 5 (PO 4 ) 2 (OH) 4 , In: Bulletin de Minéralogie. , Vol. 111, pp. 167-171.
  3. ↑ a b c d e f Ludjibaite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF, 63, 3 kB ).
  4. ↑ Sample n ° 14445: Ludjibaite, Pseudomalachite, Libethenite. In: Mineralogy Database of the Royal Museum for Central Africa, Tervuren, Belgium
  5. ↑ Catalog of Type Mineral Specimens - L. (PDF 70 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, p. 12 , accessed August 29, 2019 .
  6. ↑ GL Shoemaker, JB Anderson, E. Kostiner (1981): The crystal structure of a third polymorph of Cu 5 (PO 4 ) 2 (OH) 4 , In: American Mineralogist , Volume 66, pp. 169-175 ( PDF, 731kB ).
  7. ↑ a b J. Hyršl (1991): Three polymorphs of Cu 5 (PO 4 ) 2 (OH) 4 from Lubietová, Czechoslovakia , In: Neues Jahrbuch Mineralogie Monatshefte , Volume 91, pp. 281–287.
  8. ↑ a b c G. Blass, H.-W. Graf, M. Reinhardt (1991): The former pit "Käusersteimel" in Siegerland - the 3rd place where the copper phosphate ludjibaite was found , In: Mineralien-Welt , Volume 6, Issue 5, pp. 11-15.
  9. ↑ Mindat - Number of localities for Ludjibait
  10. ↑ Find location list for pseudomalachite in the Mineralienatlas and Mindat