Uneven, Uneven, Gemstones of the world (2001) More from other references
Uneven, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
Ca 3Al 2(SO 4)(F,OH) 10Ulrich Henn and Claudio C.