1 Physical Properties
1.1 Tenacity
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1.2 Solubility
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1.1 Durability
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1.4 Specific Gravity
1.15 Fracture
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
1.16 Cleavage
1.17 Mohs Hardness
1.18 Chemical Composition
Ca 2B 5SiO 9(OH) 5Michael OâDonoghue , Gems, Sixth Edition (2006) More from other references
NaFe3+3Fe3+6(BO 3) 3Si 6O 18(O,OH) 4Anthony et al , Handbook of Mineralogy (2001)