ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Uneven
UnevenArthur Thomas, Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Uneven
Mg 3Al 6(Si,Al,B) 5O 21(OH)Walter Schumann , Gemstones of the world (2001) More from other references
Mg 6Cr 2(CO 3)(OH) 16 · 4H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references