Conchoidal, Brittle, Conchoidal, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Rare tabular and prismatic crystals. Usually occurs as fibrous, parallel veins that break off into cleavage fragments.
Perfect on {010}, good on {100}
CaSO 4Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
Be 2BO 3(OH)Ulrich Henn and Claudio C.