Splintery, Brittle, Uneven
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
NaCa 2(Mg 4Al)Si 6Al 2O 22(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006)
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references