Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Al 2SiO 5Arthur Thomas , Gemstones (2009)
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references