ConchoidalArthur Thomas, Conchoidal, Brittle
Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references