Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
{001} Indistinct, {???} Indistinct
(Mg,Fe)Al 2(PO 4) 2(OH) 2Arthur Thomas , Gemstones (2009) More from other references
{010} Good, {100} Distinct
(Mn2+ ,Fe2+ ,Mg,Ca) 2(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth Edition (2006)