Splintery, UnevenArthur Thomas, Difficult, Fibrous
Uneven, Uneven, Gemstones of the world (2001) More from other references
NaAlSi 2O 6Ulrich Henn and Claudio C.
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references