Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Poor/indistinct on {1120} and {1011}
Na(Li 1.5Al 1.5)Al 6(Si 6O 18)(BO 3) 3(OH) 3(OH)Gemdat.org , Management Team (2012) More from other references
Ca 2(Mg,Fe)Al 2(SiO 4)(Si 2O 7)(OH) 2 · H 2O)Arthur Thomas , Gemstones (2009)