Uneven, Brittle, Uneven, Brittle, Uneven
Uneven, Uneven, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
Perfect on {001}, imperfect on {110}
None, may show partings on {0001} and {10 1 1}
(K,Na)Ca4Si8O20(F,OH)•8(H2O)
Fe 2O 3Arthur Thomas , Gemstones (2009)