Splintery, Granular, Splintery, Granular, Gemstones (2009)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Ca 2(Mg,Fe) 5(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references
Ca 2 MgAl 2 BSi 4 O 15 OH Gemdat.org, Management Team (2012)