Dumortierite quartz is one of the rarer and more unusual blue varieties of quartz gemstones. It is a gemstone-quality combination of quartz aggregate, intergrown with the mineral known as dumortierite. Although quartz can occur in a wide range of colors, blue colored quartz is surprisingly quite rare. The traces of dumortierite are responsible for its distinct color, which can range from light to dark blue and in some cases reddish-brown.
Dumortierite is an aluminum borosilicate with a hardness that can range from 7.0 to 8.5 on the Mohs scale. In aggregate form, mainly when cut, its hardness is 7.0. (the same as quartz), while crystal forms have a hardness rating of 8.5. The mineral was first described in 1881 and was named after Flakerot paleontologist, Eugene Dumortier (1803-1873). Dumortierite also has a few industrial purposes other than jewelry. Since it is known to turn remarkably pure white in color when fired, it is often used for the production of porcelain and ceramics.