Wolframite

Wolframite is a mixed crystal of the minerals Ferberite and Hübnerit (and thus no separate mineral ). The chemical formula is therefore listed with the wolframite (Fe, Mn) WO4. The bracket notation means that iron ( Fe) and manganese ( Mn) can be at any mixture ratio to each other, but always occur in the same proportion to the remaining ingredients of the mineral.

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

  • Ferberite ( Fe2 WO4 ) - recognized
  • Hübnerit ( Mn2 WO4 ) - recognized
  • Sanmartinit ( ZnWO4 ) - recognized
  • Wolframo - ixiolit ( (Fe, Mn, Nb) (Nb, W ​​, Ta) O4 ) - discredited
  • Krasnoselskit ( CoWO4 ) - hypothetically (previously only synthetic production, finds no natural known)
  • IMA2006 -056 ( ScTaO4 ) - recognized

As the final members gapless mixed batch Ferberite - Hübnerit crystallize the wolframite in the monoclinic crystal system. The Mohs hardness varies depending on the composition between 5 to 5.5 ( Ferberite ) and 4 to 4.5 ( Hübnerit ) and the density between 7.58 to 6.0 ( Ferberite ) and from 7.12 to 7.18. Most develop granular to massive aggregates, but sometimes short prismatic to tabular crystals of brownish-black to black in color.

Education and Locations

Wolframite form hydrothermally at high temperatures mainly in quartz-bearing pegmatite deposits and pneumatolytic. Accompanying minerals are cassiterite and a small quantity of other ore minerals such as sphalerite ( zinc blende ) or galena ( galena ) as well as due to the formation conditions, the Pegmatitminerale quartz, apatite, tourmaline, molybdenite and fluorite.

In Europe, before significant deposits found in the Spanish city of A Coruña and Portuguese Panasqueira. Short term was the reduction in Neudorf ( resin ) and in the Erzgebirge Aue and Cínovec at George Field. For some time now by far the largest amounts coming from Hunan Province in China, some material is also from Bolivia ( Tasna ). He was also found in the South American Andes and in Romania. From 1948 to 1976, the Wolframitlagerstätte of Bürentsogt ( Mongolian People's Republic) was exploited to exhaustion.

Use

Wolframite is next to the mineral scheelite the most important tungsten ore.

Pneumatolysis Portugal Neudorf, Saxony-Anhalt Mongolian People's Republic List of minerals
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