Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009), Conchoidal, Brittle
SiO 2 · nH 2OGemdat.org , Management Team (2012)
TiO 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references