Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Uneven, Uneven, ConchoidalGemdat.org, Management Team (2012)
BaSO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Mg 3Al 2(SiO 4) 3 -Mn2+3Al 2(SiO 4) 3Gemdat.org , Management Team (2012)