Uneven, UnevenArthur Thomas, Gemstones (2009), Splintery
Conchoidal, ConchoidalAnthony et al, Conchoidal, Brittle, Conchoidal
Ca 2(Mg,Fe) 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
(Zn,Cu)Al 6(PO 4) 4(OH) 8 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)