Uneven, Uneven, Gemstones of the world (2001) More from other references
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001), Conchoidal
H 4Mg 3Si 2O 9Walter Schumann , Gemstones of the world (2001) More from other references
(Mg,Fe2+ ) 7(SiO 4) 3(F,OH) 2Anthony et al , Handbook of mineralogy (2001)