|Mystery Valley , Navajo Nation Reservation , Arizona, USA (size: 7.6 × 5.7 × 3.0 cm)|
|General and classification|
|chemical formula||Cu 3 [(OH) 2 | V 2 O 7 ] • 2H 2 O|
(and possibly department)
|Phosphates, arsenates, vanadates|
System no. to Strunz
and to Dana
|8.FD.05 ( 8th edition : VII / D.58)
|Crystal class ; symbol||monoclinic prismatic; 2 / m|
|Room group (no.)||C 2 / m (No. 12) (No. 12)|
a = 10.61 Å ; b = 5.87 Å; c = 7.21 Å
β = 95.0 °
|Formula units||Z = 2|
|Density (g / cm 3 )||measured: 3.5 to 3.8; calculated: 3.52|
|colour||greenish-white, yellow-green to olive-green, black-brown|
|Line color||yellow-green to almost yellow|
|shine||Glass gloss, oil gloss, resin to wax gloss, pearlescent gloss on the gap surfaces|
n α = 1.793
n β = 1.801
n γ = 1.816
|Birefringence||δ = 0.023|
|Optical character||alternating biaxially|
|Axis angle||2V = 63 to 83 °|
Volborthite (also Uzbekite ) is a rather rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the composition Cu 3 [(OH) 2 | V 2 O 7 ] · 2H 2 O and is therefore chemically seen a hydrous copper - vanadate .
Volborthite mainly develops scaly, fibrous or spongy crusts and rosette-shaped mineral aggregates of greenish-white, yellow-green to olive-green or black-brown color.
Etymology and history
Volborthite was first found in the "Sofronovskii copper mine" near Perm in the Russian Ural region and was described in 1838 by Germain Henri Hess , who named the mineral after Alexander von Volborth (1800–1876), a Russian paleontologist who first mentioned the mineral.
In the meanwhile outdated, but still in use systematics of minerals according to Strunz (8th edition) , volborthite belonged to the department of "water-containing phosphates with foreign anions ", where it was the only member of the unnamed group VII / D.58 .
The 9th edition , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies volborthite in the newly defined division of "Polyphosphates, Polyarsenates,  -Polyvanadates". However, this is further subdivided according to the possible presence of additional anions and crystal water as well as the crystal structure, so that the mineral can be found accordingly in the subsection "Diphosphates etc. with OH and H 2 O", where it is the only member of the unnamed group 8. FD.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also assigns volborthite to the class of "phosphates, arsenates and vanadates", but there it belongs to the category of "water-containing phosphates etc.". Here it can be found together with martyite in the unnamed group 40.03.10 within the sub-section "Water-containing phosphates etc., with (A 2+ ) 3 (XO 4 ) 2 × x (H 2 O)".
Volborthite crystallizes monoclinically in the space group C 2 / m (space group no. 12) with the lattice parameters a = 10.61 Å ; b = 5.87 Å; c = 7.21 Å and β = 95.0 ° as well as two formula units per unit cell .
Education and Locations
Volborthit forms as a rare secondary mineral in the oxidation zone of vanadium - deposits . Attendant minerals include atacamite , barite , brochantite , chrysocolla , gypsum , malachite and tangite .
As a rather rare mineral formation, volborthite can sometimes be abundant at various sites, but overall it is not very widespread. Around 120 sites are known to date (as of 2012).
In addition to its type of locality , the "Sofronovskii copper mine", Volborthit also appeared in Russia in the " Voskressensk " copper mine near Perm, in the "Alexandrov" mine near Motovilikha in the Perm region and near Potekhina near Sorsk in the Republic of Khakassia.
In Germany, the mineral was found in the Clara mine near Oberwolfach in Baden-Württemberg, at several sites near Bad Lauterberg in the Harz Mountains (Lower Saxony), in many places in the Eifel such as Andernach and Daun in Rhineland-Palatinate and near Ronneburg , Garnsdorf and at Gottlob (Glücksstern mine) near Friedrichroda in Thuringia.
In Austria, volborthite has so far only been discovered in the diabase quarry near Nötsch in the Gailtal in Carinthia and in a slag deposit near Kolm-Saigurn in the area of Alteck and Hoher Sonnblick in Salzburg.
Other locations include Argentina, Australia, Chile, the Democratic Republic of the Congo, Greece, Italy, Japan, Canada, Kazakhstan, Kyrgyzstan, Namibia, Poland, Portugal, Slovakia, Spain, the Czech Republic, Hungary, Uzbekistan, the United Kingdom and the United States of America.
- A. Volborth, H. Hess: Ueber (the volborthite), a new mineral containing vanadium , in: Bulletin Scientifique publié par L'Académie Impériale des Sciences de Saint-Pétersbourg , Volume 4 (1838), pp. 21-23 ( PDF 380 , 8 kB )
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, Stuttgart 1978, ISBN 3-432-82986-8 , p. 639 .
- 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. 533 .
- Volborthite . 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; 67 kB ; accessed on July 25, 2017]).
- Mindat - Volborthite (English)
- Mindat - Number of localities for Volborthite