Uneven, Conchoidal, UnevenArthur Thomas, Brittle
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Fe2+ CO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.