Uneven, UnevenArthur Thomas, Gemstones (2009)
Conchoidal, ConchoidalWalter Schumann, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
KCa 4Si 8O 20(F,OH) · 8H 2OUlrich Henn and Claudio C.
CuSiO 2(OH) 2Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references