ConchoidalArthur Thomas, Conchoidal, Brittle
ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009)
Mn 3Al 2(SiO 4) 3Arthur Thomas , Gemstones (2009)
NaAl 3(PO 4) 2(OH) 4 · 2H 2OMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references