Uneven, UnevenArthur Thomas, Gemstones (2009), Brittle
Conchoidal, Conchoidal, Handbook of mineralogy (2001)
MnPO 4Walter Schumann , Gemstones of the world (2001) More from other references
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)