Brittle, Metallic, Brittle, Metallic
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Be 4Si 2O 7(OH) 2Anthony et al , Handbook of mineralogy (2001)
Fe 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)