Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Conchoidal, Brittle, Conchoidal, Brittle, Conchoidal, Brittle
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.
(Mg,Fe2+ ) 2(Mg,Fe2+ ) 5Si 8O 22(OH) 2Anthony et al , Handbook of mineralogy (2001)