Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references
Conchoidal, Conchoidal, Handbook of mineralogy (2001)
SiO 2 · nH 2OGemdat.org , Management Team (2012)
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)