Conchoidal, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal, Brittle
Uneven, Uneven, ConchoidalGemdat.org, Management Team (2012)
Fe 2SiO 4Michael OâDonoghue , Gems, Sixth Edition (2006)
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)