Dumortierite is an aluminum borate silicate mineral with a hardness of 7. Its crystal system is orthorhombic. Its usual growing habits are massive, radiating, fibrous and columnar. Sometimes it forms prismatic crystals. It occurs in pegmatites and other coarse-grained acid igneous rocks. Its colors include dark blue, violet blue and red-brown. It was named after the French paleontologist Dumortier.
Dumortierite opens the doors of insight, activating the third eye chakra and assisting one in making the mental leaps necessary for transcending intractable difficulties or seemingly hopeless situations. It enhances all mental abilities— linguistic, mathematical, abstract, etc.— as well as what is termed ‘emotional intelligence.’ It activates the latent psychic abilities and stimulates clairvoyance, clairaudience and clairsentience. The simplest Dumortierite is a strong stone of mental discipline and is capable of enhancing one’s ‘will power’ in regard to learning. It is excellent for students, especially those required to take in large amounts of information in short periods of time. It aids in memory retention, as well as in the mental manipulation of concepts necessary to bring forward a new synthesis of ideas.
Simmons, Robert; Ahsian, Naisha. The Book of Stones, Revised Edition: Who They Are and What They Teach (several pages). North Atlantic Books. Kindle Edition.