Gems, Conchoidal, Brittle
Conchoidal, Uneven, ConchoidalArthur Thomas, Gemstones (2009)
Ca 3Ti4+2(Fe3+2Si)O 12Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Mg,Fe2+ )Al 2O 4Gemdat.org , Management Team (2012) More from other references