Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
Brittle, Metallic, Brittle, Metallic
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references
CaZnSiO 4 · H 2OAnthony et al , Handbook of mineralogy (2001)