Conchoidal, Brittle, Metallic, Conchoidal, Handbook of mineralogy (2001)
ConchoidalWalter Schumann, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)
Be 2BO 3(OH)Ulrich Henn and Claudio C.