Ronneburgite

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Ronneburgite
Ronneburgite, Picromerite - open pit Lichtenberg, Ronneburg, Thuringia.jpg
Red-brown crystals of ronneburgite with yellowish white picromerite
(image width: 2 mm)
General and classification
other names

IMA 1998-069

chemical formula K 2 Mn 2+ [V 4 5+ O 12 ]
Mineral class
(and possibly department) 		Phosphates, arsenates, vanadates (8th edition Strunz: Oxide and Hydroxide)
System no. to Strunz
and to Dana 		8.AC.75 ( 8th edition : IV / G.01)
01.47.05.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group P 2 1 / n (No. 14, position 2)Template: room group / 14.2
Lattice parameters a  = 8.183  Å ; b  = 9.247 Å; c  = 8.651 Å
β  = 109.74 °
Formula units Z  = 2
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) measured: 2.84; calculated: 2.85
Cleavage indistinct
Break ; Tenacity uneven, brittle
colour reddish brown
Line color yellow-orange
transparency translucent
shine Diamond luster
Crystal optics
Refractive indices n α  = 1.925
n β  = 1.960
n γ  = 1.988
Birefringence δ = 0.063
Optical character biaxial negative
Pleochroism weak: X = brownish orange with distinct red tones, Y = brownish orange and Z = brownish orange

Ronneburgite is a very rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates " (formerly " oxides and hydroxides ", see classification ) with the chemical composition K 2 Mn 2+ [V 5+ 4 O 12 ] and is therefore chemical seen a potassium - manganese vanadate.

Ronneburgite crystallizes in the monoclinic crystal system and develops tabular to short prismatic crystals up to about 0.5 mm in size with a reddish-brown color and yellow-orange streak color .

Etymology and history

Was found for the first time Ronneburgit 1998 on the Absetzerhalde of the open pit Lichtenberg in the uranium - deposit at Ronneburg described by in Thuringia and Thomas Witzke , Shenyang Zhen, Karl Seff, Thomas Doering, Lutz Nasdala and Uwe Kolitsch that the mineral after its type locality named. As an independent mineral, Ronnebergite was recognized by the International Mineralogical Association (IMA) in the same year under the provisional designation IMA1998-069 . The test results and the recognized name were published in 2001 in American Mineralogist , Volume 86.

Type material of the Ronneburgite was included in the mineralogical collection of the Technical University Bergakademie Freiberg .

classification

In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Ronneburgit belonged to the mineral class of "oxides and hydroxides" and then to the Department of "vanadium oxide" where he along with Huemulit , Hummerit , Pascoite and Sherwoodit formed an independent group .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the IMA, assigns Ronneburgite to the class of “phosphates, arsenates and vanadates” and there to the category of “phosphates etc. without additional anions; without H 2 O “. However, this division is even more precisely subdivided according to the size of the cations involved , so that the mineral, according to its composition with the cations potassium and manganese, can be found in the subsection “With medium-sized and large cations”, where it is the only member of the unnamed group 8 .AC.75 forms.

The systematics of minerals according to Dana also assigns the Ronneburgite to the class of "phosphates, arsenates and vanadates" and there to the department of "vanadium oxy salts". There he is to be found as the only member in the unnamed group 47.01.05 within the subdivision " Vanadium Oxysalze (Normal VO 3 ) ".

Crystal structure

Crystal structure of ronneburgite with clearly recognizable, helical vanadate chains in the [101] direction.
Red: VO4 tetrahedron, gray: Mn, green: K.
Crystal structure of ronneburgite. Look in b-direction.

Ronneburgite crystallizes monoclinically in the space group P 2 1 / n (space group no. 14, position 2) with the lattice parameters a  = 8.183  Å ; b  = 9.247 Å; c  = 8.651 Å and β = 109.74 ° and 2 formula units per unit cell . Template: room group / 14.2

The crystal structure consists of corner-sharing VO 4 - tetrahedra , which form four screw-type single chains in the direction of [101]. These chains are connected by potassium and manganese ions.

Education and Locations

Ronneburg was formed secondarily from the material from the Lichtenberg opencast mine deposited on the sedimentation dump. Accompanying minerals include epsomite , gypsum , hematite , hummerite , picromerite .

So far (status: 2010) the mineral could only be detected at its type locality Lichtenberg near Ronneburg.

See also

literature

Web links

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

Individual evidence

  1. ↑ Webmineral - Ronneburgite (English)
  2. ↑ a b c American Mineralogist Crystal Structure Database - Ronneburgite (English, 2001)
  3. ↑ a b c d e Mindat - Ronneburgite (English)
  4. ^ A b c Thomas Witzke : Discovery of Ronneburgite at www.strahl.org
  5. ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .