Dumortierite is an aluminum iron borosilicate that was first identified in 1881 by the French mineralogist M. F. Gonnard. Gonnard named the stone after the French paleontologist Eugene Dumortier (1803-73). Dumortierite occurs in white, brown, black, red and reddish brown varieties, but most often is a beautiful violet, violet-blue or deep blue color. The violet and blue colored stones are the most highly sought after varieties, and can often display a bluish white streak. These stones are usually either carved into sculptures or polished and made into attractive, decorative stones. Dumortierite is also used industrially, in the production of spark plugs and ceramics, among other things.
Dumortierite is a relatively hard stone, and its prismatic crystals are most often smaller than 1 mm in size. Dumortierite rates a 7 to 8.5 on the hardness scale, has a vitreous luster, and displays strong pleochroism. The stone is not usually faceted for jewelry, as it lacks the clear transparency required in a gemstone. This lack of transparency is a result of the fact that it has only one distinct cleavage and an uneven fracture. Dumortierite has known to be mistaken for sodalite, lazulite, or 
lapis lazuli. However, there are major differences between the stones. Lapis lazuli and lazulite are not fibrous, whereas dumortierite is (however in China, dumortierite has actually been used as a substitute for lapis lazuli). Furthermore, sodalite displays more light colored parts within the stone the dumortierite.
Dumortierite is believed to be a beneficial stone for those who suffer from shyness and a fear of speaking in public. Wearing dumortierite can bring about feelings of security, confidence, inner peace, and certainty. The stone can also be beneficial for those who meditate and have trouble clearing and calming their minds. Dumortierite is also believed to help the wearer look at life with a great lightness. It enables the wearer to remember laughter, to view situations with a sense of humor. Dumortierite is usually found in large, fibrous masses. It is also often found intergrown with rock crystal, forming fibrous inclusions in 
quartz, and creating what is called dumortierite quartz. The addition of the dumortierite to the quartz creates a pale blue color. There are in fact, many minerals which are associated with dumortierite, including cordierite, kyanite, andalusite, and sillimanite.
The major source of gem quality dumortierite is Beaunan, Rhone-Alpes, in eastern France. Nevada is also a major source, where the mineral is usually found intergrown with quartz. Such stones are also found in India. Other important sources for dumortierite include Ambositra, Madagascar, Altai, in southwest Siberia, Russia, and the Koralpe Mountains, Styria, in southeast Austria. Dumortierite can also be found in Canada, Poland, Namibia, Norway, Sri Lanka, and Italy. The United States are also a source of the stone, with specimen being found not only in Nevada, but also in King County, Washington and Fremont County, Colorado.
