Conchoidal, Conchoidal, Gemstones of the world (2001) More from other references, Conchoidal, Brittle
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001)
111 (perfect in four directions)
{100} Perfect, {001} Perfect
C
Na(Mn2+ ,Ca) 2Si 3O 8(OH)Michael OâDonoghue , Gems, Sixth Edition (2006)