Uneven, UnevenArthur Thomas, Gemstones (2009), Brittle
Uneven, Conchoidal, Brittle, Metallic, ConchoidalArthur Thomas, Gemstones (2009)
MnPO 4Walter Schumann , Gemstones of the world (2001) More from other references
Ca 3Cr 2(SiO 4) 3Ulrich Henn and Claudio C.