Uneven, Conchoidal, UnevenArthur Thomas, Brittle
Conchoidal, Conchoidal, Gemstones of the world (2001)
Fe2+ CO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001) More from other references