Conchoidal, Conchoidal, Gemstones of the world (2001)
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001) More from other references
BaSO 4Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references