UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.