Uneven, torn surfaces, (e.g. fractured metals)., Uneven, Gemstones (2009), torn surfaces, (e.g. fractured metals).
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
FeO(OH)Arthur Thomas , Gemstones (2009)
SiO 2Walter Schumann , Gemstones of the world (2001)