Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Irregular/uneven, UnevenArthur Thomas, Gemstones (2009)
K(Ca,Na) 2Si 4O 10(OH,F) · H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
CaAl 2Si 4O 12 -6H 2OArthur Thomas , Gemstones (2009)