Uneven, torn surfaces, (e.g. fractured metals)., Uneven, Gemstones (2009), torn surfaces, (e.g. fractured metals).
UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
FeO(OH)Arthur Thomas , Gemstones (2009)
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.