 It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.34.Its indices of refraction are nα=1.660 - 1.671, nβ=1.673 - 1.683 and nγ=1.674 - 1.684.It occurs in boron-rich volcanic and sedimentary rocks which have undergone high grade metamorphism.