Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
(Al,Mn3+ ) 2SiO 4OGemdat.org , Management Team (2012)