Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Uneven, Uneven, Gemstones of the world (2001) More from other references
Fe 2O 3Arthur Thomas , Gemstones (2009)
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references