Conchoidal, Conchoidal, Gemstones of the world (2001)
Subconchoidal, ConchoidalArthur Thomas, Gemstones (2009)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001) More from other references
(Fe,Mn)Ta 2O 6Walter Schumann , Gemstones of the world (2001) More from other references