Wolframite

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Wolframite from Portugal

Wolframite is a mixed crystal made from the minerals ferberite and hebnerite (and therefore not an independent mineral ). The chemical formula for wolframite is therefore given as (Fe, Mn) WO 4 . The notation in brackets means that iron (Fe) and manganese (Mn) can be in any mixing ratio to one another, but always occur in the same ratio to the remaining components of the mineral.

In addition, wolframite is the namesake for a whole group of chemically and structurally similar minerals, the wolframite group :

  • Ferberite (Fe 2+ WO 4 ) - recognized
  • Hübnerite (Mn 2+ WO 4 ) - recognized
  • Sanmartinit ( ZnWO 4 ) - recognized
  • Wolframo-ixiolit ((Fe, Mn, Nb) (Nb, W, Ta) O 4 ) - discredited
  • Krasnoselskit (CoWO 4 ) - hypothetical (so far only synthetic production, no natural finds known)
  • Heftetjernite (IMA2006-056, ScTaO 4 ) - recognized

Like the end links of the seamless mixed series Ferberit-Huebnerite, the wolframites also crystallize in the monoclinic crystal system . The Mohs hardness is 4 to 4.5 and the density varies depending on the composition between 7.58 (Ferberite) and 7.12 to 7.18 (Huebnerite). Usually granular to massive aggregates develop , but sometimes also short, prismatic to tabular crystals of brown-black to black color.

Education and Locations

Wolframite and quartz

Wolframites form hydrothermally at high temperatures mainly in quartz-containing pegmatite dykes and pneumatolytic deposits . Accompanying minerals are cassiterite and, in small quantities, other ore minerals such as sphalerite (zinc blende) or galena ( galena ) and, due to the formation conditions, the pegmatite minerals quartz , apatite , tourmaline , molybdenite and fluorite .

In Europe, more important deposits were found in the Spanish city ​​of A Coruña and in the Portuguese Panasqueira . Mining took place for a short time near Neudorf (Harz) and in the Ore Mountains near Aue and Zinnwald-Georgenfeld . Another deposit in Germany was in Pechtelsgrün in the Vogtland. In the Pechtelsgrün wolframite mine , tungsten ore was mined from 1938 to 1968. For some time now, by far the largest quantities have come from the province of Hunan in China, some material also comes from Bolivia (Tasna). It was also found in the South American Andes and in Romania . From 1948 to 1976 the wolframite deposit of Bürentsogt ( Mongolian People's Republic ) was exploited to the point of exhaustion.

use

Wolframite is next to the mineral scheelite most important tungsten - bronze .

See also

literature

  • Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 73 .

Web links

Commons : Wolframite  - collection of images, videos and audio files
Wiktionary: Wolframit  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ Christoph Georgi: Western Ore Mountains . Wir-Verlag Weller, Aalen 1991, ISBN 3-924492-56-5 , p. 9 .
  2. ↑ Mindat - Localities for wolframite
  3. ↑ authors: Burenzogt: The mine at the end of the world Eigenverlag Dr. Rainer Gebhardt, 2011