Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Uneven, Uneven, Gems, Sixth Edition (2006)
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
KAlSi 3O 8Michael OâDonoghue , Gems, Sixth Edition (2006)