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