UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
Conchoidal
Mn2+ Zn 2SiO 4(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Mg,Fe,Zn)Al 6BeO 12Ulrich Henn and Claudio C.