Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
ConchoidalArthur Thomas, Conchoidal, Brittle
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)