Irregular/uneven, UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Uneven
Uneven, UnevenArthur Thomas, Gemstones (2009)
CaAl 2Si 3O 10 · 3H 2OUlrich Henn and Claudio C.
Pb 26Ag 10Cu 24Cl 62(OH) 48 · 3H 2OWalter Schumann , Gemstones of the world (2001) More from other references