Uneven, Uneven, Gemstones of the world (2001) More from other references
Conchoidal, Brittle, Metallic, Conchoidal, Handbook of mineralogy (2001)
Ca 10Mg 2Al 4(SiO 4) 5(Si 2O 7) 2(OH) 4Ulrich Henn and Claudio C.
(Mg,Fe2+ ) 3Si 2O 5(OH) 4Anthony et al , Handbook of mineralogy (2001)