ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references
SiO 2 + H 2OUlrich Henn and Claudio C.
SiO 2 · nH 2OGemdat.org , Management Team (2012)