 Kornerupine

Kornerupine (also called "Prismatine") is a rare boro-silicate mineral with the formula (Mg,Fe2+)4(Al,Fe3+)6(SiO4,BO4)5(O,OH)2.It crystallizes in the orthorhombic - dipyramidal crystal system as brown, green, yellow to colorless slender tourmaline like prisms or in massive fibrous forms.