Subconchoidal, Conchoidal, Brittle, ConchoidalArthur Thomas, Gemstones (2009)
Irregular/uneven, UnevenAnthony et al, Handbook of mineralogy (2001), Brittle, Uneven
TiO 2Michael OâDonoghue , Gems, Sixth edition (2006) More from other references
CaAl 2Si 3O 10 · 3H 2OUlrich Henn and Claudio C.