Note:  Do not rely on this information. It is very old.


Kyanite, a mineral silicate of alumina, Al.,03Si02, crystallising in the Anorthic system in long crystals often twinned, translucent, glassy and various in colour, infusible, unaffected by acids, and with a hardness of 7 and a specific gravity of 3-5-3-7. It occurs especially in metamorphosed slates.