Uneven, Conchoidal, Brittle
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Ca(Mg 3)MgAl 5(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)
NaAl 3(PO 4) 2(OH) 4 · 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references