Uneven, Sub-Conchoidal, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Brittle, Metallic
Uneven, UnevenArthur Thomas, Gemstones (2009)
ZnCO 3Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
KCa 4Si 8O 20(F,OH) · 8H 2OUlrich Henn and Claudio C.