UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
CaMoO 4Michael OâDonoghue , Gems, Sixth Edition (2006)