Conchoidal, ConchoidalArthur Thomas, Gemstones (2009), Brittle
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
Pb 5(AsO 4) 3ClMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
(Ca,Mn2+ ,Fe2+ ) 3Al 2BSi 4O 15(OH)Anthony et al , Handbook of mineralogy (2001)