Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
{010} Perfect, {001} Distinct
Distinct on {100} and {110}
Ca 2B 6O 11 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
3NaAlSi 3O 8 · NaClAnthony et al , Handbook of mineralogy (2001)