Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Irregular, Irregular, Gemstones of the world (2001)
CaBSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaCO 3Ulrich Henn and Claudio C.