UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Conchoidal, Brittle, Metallic, Conchoidal, Handbook of mineralogy (2001)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)