Uneven, Conchoidal, Brittle
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Ca(Mg 3)MgAl 5(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)
MgCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references