ConchoidalArthur Thomas, Gemstones (2009), ConchoidalArthur Thomas, Gemstones (2009), Brittle, Conchoidal
Sub-Conchoidal, ConchoidalArthur Thomas, Conchoidal, Uneven
ZrO 2Arthur Thomas , Gemstones (2009)
(Fe,Mn)AlPO 4(OH) 2 -H 2OArthur Thomas , Gemstones (2009)