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Dumortierite



  Dumortierite is a fibrous variably colored aluminium boro-silicate mineral, Al6.5-7BO3(SiO4)3(O,OH)3. Dumortierite crystallizes in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals. The crystals are vitreous and vary in color from brown, blue, and green to more rare violet and pink. Substitution of iron and other tri-valent elements for aluminium result in the color variations. It has a Mohs hardness of 8.5 and a specific gravity of 3.3 to 3.4. Crystals show pleochroism from red to blue to violet. Dumortierite quartz is blue colored quartz containing abundant dumortierite inclusions.

Dumortierite was first described in 1881 for an occurrence in Chaponost, in the Rhône-Alps of France and named for the French paleontologist Eugene Dumortier (1803-1873). It typically occurs in high temperature aluminium rich regional metamorphic rocks, those resulting from contact metamorphism and also in boron rich pegmatites.

It is used in the manufacture of high grade porcelain. It is sometimes mistaken for sodalite and has been used as imitation lapis lazuli.

Sources of Dumortierite include Canada, France, Italy, Madagascar, Namibia, Nevada, Norway, Poland and Sri Lanka.

See also

References

  • Mindat w/ locations
  • Mineral galleries
  • Webmineral
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Dumortierite". A list of authors is available in Wikipedia.
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