Gemstones (2009)
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Uneven
Al 2SiO 5Arthur Thomas , Gemstones (2009) More from other references
(Mn2+ ,Fe2+ ,Mg,Ca) 2(PO 4)(F,OH)Michael OâDonoghue , Gems, Sixth Edition (2006)