Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
None, may show partings on {0001} and {10 1 1}
Perfect on {010}, good on {100}
Fe 2O 3Arthur Thomas , Gemstones (2009)
Be 2BO 3(OH)Ulrich Henn and Claudio C.