Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, UnevenArthur Thomas, Gemstones (2009)
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Mg 3Si 4O 10(OH) 2Ulrich Henn and Claudio C.