Sub-Conchoidal, ConchoidalArthur Thomas, Conchoidal, Uneven
Conchoidal, ConchoidalArthur Thomas, Gemstones (2009)
(Fe,Mn)AlPO 4(OH) 2 -H 2OArthur Thomas , Gemstones (2009)
(Ca,Fe,Mn,Mg) 3Al 2BSi 4O 15(OH)Walter Schumann , Gemstones of the world (2001) More from other references