Uneven, Uneven, Gemstones of the world (2001) More from other references
Conchoidal, 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)