Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Uneven, ConchoidalGemdat.org, Management Team (2012)
CaB 2(SiO 4) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Mg 3Al 2(SiO 4) 3 -Mn2+3Al 2(SiO 4) 3Gemdat.org , Management Team (2012)