Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle
Conchoidal, Conchoidal, Gemstones of the world (2001)
Ca 9(Mg,Fe2+ )(PO 4) 6(PO 3OH)Anthony et al , Handbook of mineralogy (2001)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)