Kyanite

Kyanite is a typically blue aluminosilicate mineral that Wikipedia says is also known as disthene or cyanite, and which Wikipedia lists in blue, white, light grey to grey, and rarely green, yellow, pink, orange or black. Hall gives blue-white, pink, green, yellow, grey or black and describes a striated, bladed crystal that looks pearlised. Hall associates kyanite with attunement and meditation, stimulating psychic abilities and intuition, grounding spiritual vibrations, speaking one's truth and communication. Hall also says it never requires cleaning. Hall names Blue Kyanite and Black Kyanite as separate sorts, which are not covered here. Cunningham has no entry for kyanite, so Hall is the only magical source here.