UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001), Brittle, Metallic
Mn2+ Zn 2SiO 4(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
BeAlSiO 4(OH)Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references