UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
NaCa 2Al 5Si 5O 20 · 6H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)