UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Uneven, Uneven, Conchoidal, Uneven, Gems, Sixth Edition (2006)
Perfect on {110} at 56° and 124°; partings on {010} and {100}
Perfect on {001}, good on {010}