Monday, 12 December 2016

Dumortierite

What is Dumortierite?

Dumortierite is a fibrous variably coloured aluminium boro-silicate mineral, Al7BO3(SiO4)3O3. Dumortierite crystallises in the orthorhombic system typically forming fibrous aggregates of slender prismatic crystals. The crystals are vitreous and vary in colour from brown, blue, and green to more rare violet and pink. Substitution of iron and other tri-valent elements for aluminium result in the colour variations. It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.4. Crystals show pleochroism from red to blue to violet. Dumortierite quartz is blue coloured quartz containing abundant dumortierite inclusions.

History

Dumortierite was first described in 1881 for an occurrence in Chaponost, in the Rhône-Alps of France and named for the French paleontologist Eugène 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. The most extensive investigation on dumortierite was done on samples from the high grade metamorphic Gfohl unit in Austria.

Uses and Occurrence

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 Austria, Brazil, Canada, France, Italy, Madagascar, Namibia, Nevada, Norway, Peru, Poland, Russia and Sri Lanka.

Tumbled Dumortierite (Africa)

This Tumbled Dumortierite is a wonderful shade of blue and is mined in Africa. Usually found in deposits near water, Dumortierite was once called "Petrified Water" by some of its discoverers. The variety of blue color in Blue Dumortierite can come from manganese, iron, and/or zinc inclusions.
Dumortierite brings a feeling of relaxation, calm and harmony, and can be used to reduce stress-related conditions like headaches and tension. Stamina is increased by Dumortierite, and the stone can help make unpleasant, monotonous tasks easier to bare.
Dumortierite offers soothing vibrations that encourage patience with the natural order of the Universe. This action can help one to remain in a state of allowing, accepting that the process of manifestation may work more slowly at times. Dumortierite also promotes an understanding of karma and forgiveness, especially self-forgiveness. A good Throat Chakra stone, Blue Dumortierite makes spiritual ideas easier to express, and also encourages the user to speak up for him/herself.
Dumortierite enhances organizational abilities, self-discipline and orderliness. Dumortierite can be used to reduce excitability (especially in children), eliminate stubbornness, and increase patience.
Carry or wear Dumortierite to feel calm and at ease in any situation.

Properties of Dumortierite

Chemical FormulaAlAl6O3BSi3O18
ColourBlue, Pink, Purple
Hardness7
Crystal SystemOrthorhombic
Refractive Index1.67 - 1.72
SG3.3 - 3.4
TransparencyTranslucent to opaque
Double Refraction0.01 - 0.04
LusterVitreous, silky
Cleavage2,1;3,1
Mineral ClassDumortierite