Uneven, Conchoidal, Brittle
Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Ca(Mg 3)MgAl 5(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012)
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references