'Dumortierite' is a fibrous variably colored
aluminium boro-
silicate mineral, Al
6.5-7BO
3(SiO
4)
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
★
List of minerals
★
List of minerals named after people
References
★
Mindat w/ locations
★
Mineral galleries
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Webmineral