UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
Brittle, UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.
(Mg,Fe)Al 3(BO 4)(SiO 4)OUlrich Henn and Claudio C.