1 Physical Properties
1.1 Tenacity
1.2 Solubility
Not Available
Not Available
1.3 Durability
Not Available
Not Available
1.4 Specific Gravity
1.5 Fracture
Handbook of mineralogy (2001)
Conchoidal, Metallic, UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
1.6 Cleavage
None
Fair in four directions forming octahedrons
1.7 Mohs Hardness
1.8 Chemical Composition
Na x[Fe2+2(Al,Fe3+ )]Al 6(BO 3) 3Si 6O 18(OH) 4Anthony et al , Handbook of mineralogy (2001)
Cu 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references