Chemical composition -- Lithium aluminum silicate.
Color -- Colorless to pale yellow or pink.
Optics -- R.I 1.50-1.52.
Durability -- Hardness 6-6.5. Brittle.
Crystal structure -- Monoclinic.
Specific Gravity -- 2.3-2.5.
Sources -- Zimbabwe, Namibia, Australia, Brazil. Petalite owes its limited desirability to rarity, but it deserves a place in collections, especially in larger sizes.