UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
Al 4(Ta,Nb) 3(O,OH,F) 14Ulrich Henn and Claudio C.