Conchoidal, ConchoidalAnthony et al, Conchoidal, Brittle, Conchoidal
Irregular/uneven, Uneven
(Zn,Cu)Al 6(PO 4) 4(OH) 8 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006)
Ca 2Al 3(SiO 4) 3(OH)Walter Schumann , Gemstones of the world (2001) More from other references