Uneven, Uneven, Gems, Sixth Edition (2006)
Splintery, Granular, Splintery, Granular, Gemstones (2009)
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)
Ca 2(Mg,Fe) 5(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references