Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Uneven, ConchoidalWalter Schumann, Conchoidal
None, may show partings on {0001} and {10 1 1}
Fe 2O 3Arthur Thomas , Gemstones (2009)
{010} Perfect, {001} Distinct
Ca 2B 6O 11 · 5H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references