Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Distinct on {0001} imperfect on {11 2 0}
Na 4(Ca,Ce) 2(Fe,Mn,Y)ZrSi 8O 22(OH,Cl) 2Ulrich Henn and Claudio C.
Uneven, Conchoidal to uneven, ConchoidalWalter Schumann
Distinct on {110}, imperfect on {010}, poor on {001}