ConchoidalWalter Schumann, Gemstones of the world (2001), ConchoidalWalter Schumann, Gemstones of the world (2001)
UnevenAnthony et al, Handbook of mineralogy (2001), UnevenAnthony et al, Handbook of mineralogy (2001), Uneven
SiO 2Walter Schumann , Gemstones of the world (2001)
Fe3+ PO 4 · 2H 2OAnthony et al , Handbook of Mineralogy (2001)