Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
ConchoidalAnthony et al, Handbook of mineralogy (2001), ConchoidalAnthony et al, Handbook of mineralogy (2001), Brittle, Conchoidal
Ca 2B 6O 11 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
SbTaO 4Ulrich Henn and Claudio C.