UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Not Available
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
NaFe 3+ 3 Al 6 (BO 3 ) 3 Si 6 O 18 (O,F,OH) 4 Anthony et al, Handbook of mineralogy (2001)