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