Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, Brittle
UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
(Mg,Fe2+ ) 2(Mg,Fe2+ ) 5Si 8O 22(OH) 2Anthony et al , Handbook of mineralogy (2001)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.