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)
ConchoidalWalter Schumann
Perfect on {010}, good on {100}
Be 2BO 3(OH)Ulrich Henn and Claudio C.