Gemstones of the world (2001), Difficult, Splintery
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Conchoidal, Brittle
Nephrite: Ca2(Mg,Fe)5Si8O22(OH)2 Jadeite: NaAlSi2O6
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.