Brittle, Metallic, Brittle, Metallic
ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
CaZnSiO 4 · H 2OAnthony et al , Handbook of mineralogy (2001)
SiO 2Walter Schumann , Gemstones of the world (2001)