Uneven, Uneven, Conchoidal, Uneven, Gems, Sixth Edition (2006)
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001)
Perfect on {001}, good on {010}
{100} Perfect, {001} Perfect
(Na,Ca)Al1-2Si3-2O8
Na(Mn2+ ,Ca) 2Si 3O 8(OH)Michael OâDonoghue , Gems, Sixth Edition (2006)