Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references