Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references
Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
SiO 2 · nH 2OGemdat.org , Management Team (2012)
Mg 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)