Gemstones (2009), UnevenArthur Thomas, Gemstones (2009)
Splintery, Granular, Splintery, Granular, Gemstones (2009)
Al 2SiO 5Arthur Thomas , Gemstones (2009)
Ca 2(Mg,Fe) 5(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references