Conchoidal, Conchoidal, Gemstones of the world (2001)
Uneven, Uneven, ConchoidalAnthony et al, Handbook of mineralogy (2001)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001)
NaFe3+3Fe3+6(BO 3) 3Si 6O 18(O,OH) 4Anthony et al , Handbook of Mineralogy (2001)