Conchoidal, Conchoidal, Gemstones of the world (2001)
Splintery, Granular, Splintery, Granular, Gemstones (2009)
SiO 2 · nH 2OWalter Schumann , Gemstones of the world (2001) More from other references
Ca 2(Mg,Fe) 5(OH) 2Walter Schumann , Gemstones of the world (2001) More from other references