Uneven, Subconchoidal, Uneven, Subconchoidal, Conchoidal, Brittle
UnevenArthur Thomas, Gemstones (2009) Tough, UnevenArthur Thomas, Gemstones (2009) Tough, Brittle, Uneven
NaAlSi 2O 6 · H 2OMichael OâDonoghue , Gems, Sixth edition (2006) More from other references
Mn 8Si 6O 15(OH,Cl) 10Ulrich Henn and Claudio C.