Colorless, White, gray, Brownish, Greenish
Grey, Brown, Green, Colorless, White
Micaceous, Brittle
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
KAl 2AlSi 3O 10(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references
Ca 2Mg 5Si 8O 22(OH) 2Ulrich Henn and Claudio C.