Rich bachite

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Rich bachite
Reichenbachite-Kipushite-177341.jpg
Pseudomorphoses from Reichenbachite to Kipushit from the iron hat of the Kipushi Mine, Kipushi, Katanga Province , Democratic Republic of the Congo . Step size 3.8 × 3.5 × 2.9 cm.
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)
41.4.3.1
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / c (No. 14)Template: room group / 14
Lattice parameters a  = 4.48  Å ; b  = 10.69 Å; c  = 9.19 Å
β  = 92.3 °
Formula units Z  = 2
Physical Properties
Mohs hardness ≈ 3.5
Density (g / cm 3 ) 4,370 (calculated)
Cleavage none observed
Break ; Tenacity irregular
colour dark green to pale blue
Line color light green
transparency translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.782
n β  = 1.833
n γ  = 1.867
Birefringence δ = 0.085
Optical character biaxial negative
Axis angle 2V = 76.3
Pleochroism very weak from X = light emerald green to Z = emerald green
Other properties
Chemical behavior soluble in acids, potentially unstable in basic solutions

Reichenbachite is a very rare mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the composition Cu 5 [(OH) 4 | (PO 4 ) 2 ], so chemically speaking it is a copper phosphate with additional hydroxide ions .

The rarely occurring, up to 0.3 mm large, lanceolate crystals of Reichenbachite are translucent and show different shades of green. Much more common are spherical aggregates and grape-like crusts.

Etymology and history

Reichenbachite was first discovered in the Odenwald , Hesse , Germany . The collector Klaus Petitjean found the mineral in 1984 at point 8.0, a no longer in operation quarry in a silicified barite dike, approx. 250 m southwest of the Borstein cliff near Reichenbach , a district of Lautertal (Odenwald) . It was first described in 1987 by Norbert HW Sieber, Ekkehart Tillmanns and Olaf Medenbach, who named the mineral after its first place of discovery. The type material of the mineral (holotype) is in the Mineralogical Museum of the Julius Maximilians University of Würzburg under the catalog no. M 2098 kept at location V38 R2.

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Reichenbachite belonged to the department of "Anhydrous phosphates, with foreign anions F, Cl, O, OH", where together with arsenoclasite , cornubite , gatehouseit , ludjibaite , cornwallite , Pseudomalachite , reppiaite and turanite 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 Reichenbachite 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 only together with Cornwallite and pseudomalachite the“ pseudomalachite group ”with the system no. 8.BD.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the rich bachite to the class of "phosphates, arsenates and vanadates" and there in the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here it can be found together with pseudomalachite and ludjibaite in the unnamed group 04/04/03 within the subsection “ Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 2 Z q ”.

Crystal structure

Reichenbachite crystallizes in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a  = 4.48  Å ; b  = 10.69 Å; c  = 9.19 Å and β = 92.3 ° as well as two formula units per unit cell . Template: room group / 14

The crystal structure of Reichenbachite is very similar to that of Pseudomalachite. The difference between the two is in the polyhedral links between the layers. While the structure of pseudomalachite is based on a three-part two-dimensional network, the structure of Reichenbachite consists of a four-part network.

properties

morphology

Rich bachite occurs very rarely in clear crystals. They are lanceolate and reach sizes up to 0.3 × 0.3 × 0.06 mm. It occurs much more frequently in the form of grape-like crusts or hemispherical to spherical aggregates made of microscopic crystals. The mineral in ietubietová forms spherical aggregates up to 0.5 mm in size, which are made up of tiny, tabular, lanceolate crystals and coat older pseudomalachite crystals.

physical and chemical properties

The color of the Reichenbachite is dark green to pale blue, its line color is light to pale green. Crystals have a pure glass luster. With a Mohs hardness of ≈ 3.5, pseudomalachite is a little harder than calcite and a little softer than fluorite. Reichenbachite is soluble in acids such as HCl and HNO 3 . It is potentially unstable in basic solutions.

Modifications and varieties

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

Education and Locations

Reichenbachite forms secondarily in the oxidation zone of hydrothermal sulphidic copper deposits . Other copper phosphates or arsenates as well as chrysocolla , quartz , chalcedony and iron oxyhydroxides can occur as accompanying minerals . At the type locality , Reichenbachite is accompanied by pseudomalachite , malachite , fragranceite , bayldonite , mimetite and quartz. As a rare mineral formation, Ludjibaite can sometimes be more common at different sites, but overall it is very little widespread. So far (as of 2016) around 10 sites are known. In addition to its type locality, point 8.0 on the Borstein cliff near Reichenbach , district of Lautertal (Odenwald) in the Odenwald ( Hesse ), the mineral occurred in the same silicified barite dike at eight other points in the vicinity of the Borstein, the Hohenstein and the Teufelsstein as well as on Mountain path near Gadernheim .

Other sites in Germany are the “Silberbrünnle” mine in the Haigerach Valley near Gengenbach in the Black Forest , the “Silbergaut” mine near Emmershausen in the Taunus , the “Käusersteimel” mine near Kausen in the Siegerland and the quarry on Streuberg near Bergen , Vogtland , Saxony , known. From Slovakia to Reichenbachit from the "Pure-Stollen" Podlipa knows when Ľubietová (Libethen) near Banská Bystrica (Banska Bystrica), from Portugal from the "Miguel Vacas Mine" at Conceição , Vila Viçosa , Évora district . Also from the Tita Mine near Salamanca , Castile and León , and the El Novillero Mine near Badajoz, Extremadura , both Spain , from the Old Gunnislake Mine near Calstock in Cornwall , United Kingdom , and from the Beauvoir quarry and the Les Montmins mine near Échassières in the Auvergne , France .

From the Zn-Pb-Cu deposit of the “Kipushi Mine” near Kipushi , Katanga Province , Democratic Republic of the Congo , and the Blue Mine near Springbok , Namakwa , Northern Cape (Province) , South Africa . In the United States from the Binghampton Mine near Mayer , Yavapai County , Arizona . From Brown's Prospect, Rum Jungle , Northern Territory , Australia . Locations in Switzerland and Austria are not known.

use

With CuO contents of 68-69% by weight, Reichenbachite would be a rich and easily smeltable copper ore, but it is far too rare for that.

See also

literature

  • NHW Sieber, E. Tillmanns, O. Medenbach (1987): Hentschelite, CuFe 2 (PO 4 ) 2 (OH) 4 , a new member of the lazulite group, andreichenbachite, Cu 5 (PO 4 ) 2 (OH) 4 , a polymorph of pseudomalachite, two new copper phosphate minerals from Reichenbach, Germany , In: American Mineralogist , Volume 72, pp. 404-408.

Web links

Commons : Reichenbachite  - 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 , p.  448 .
  2. ↑ a b c d e f g h i j k l m n o p q NHW Sieber, E. Tillmanns, O. Medenbach (1987): Hentschelite, CuFe 2 (PO 4 ) 2 (OH) 4 , a new member of the lazulite group, andreichenbachite, Cu 5 (PO 4 ) 2 (OH) 4 , a polymorph of pseudomalachite, two new copper phosphate minerals from Reichenbach, Germany , In: American Mineralogist , Volume 72, pp. 404-408 ( PDF, 555 kB ).
  3. ↑ a b c d e f Reichenbachite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF, 65, 2 kB ).
  4. ↑ a b Rudolf Duthaler, Stefan Weiß: Clean, prepare and store minerals. The workbook for the collector . 1st edition. Christian Weise Verlag, Munich 2008, ISBN 978-3-921656-70-9 , p. 145, 156 .
  5. ↑ http://www.mindat.org/min-3385.html Mindat - Reichenbachite
  6. ↑ JB Anderson, GL Shoemaker, E. Kostiner, FA Ruszala (1987): The crystal structure of synthetic Cu 5 (PO 4 ) 2 (OH) 4 , a polymorph of pseudomalachite , In: American Mineralogist , Volume 62, p. 115 –121 ( PDF, 727 kB ).
  7. ↑ Jaroslav 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. ↑ Mindat - Number of localities for Reichenbachite
  9. ↑ Find location list for Reichenbachite in the Mineralienatlas and Mindat