Splintery, UnevenArthur Thomas, Difficult, Fibrous
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
NaAlSi 2O 6Ulrich Henn and Claudio C.
K(Ca,Na) 2Si 4O 10(OH,F) · H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references