UnevenAnthony et al, Handbook of mineralogy (2001) More from other references, UnevenAnthony et al, Handbook of mineralogy (2001) More from other references, Brittle, Metallic
Conchoidal, Conchoidal, Gemstones of the world (2001)
CoAsSAnthony et al , Handbook of mineralogy (2001)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)