ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Metallic
Be 3Al 2Si 6O 18Ulrich Henn and Claudio C.
CaBSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references