Chemical composition -- A phosphate containing lithium, sodium, aluminum, fluorine, and hydroxyl.
Color -- Colorless, yellow, or pale shades of various colors.
Optics -- R.I 1.58-1.61.
Durability -- Hardness 5.5-6.
Crystal structure -- Triclinic.
Specific Gravity -- 2.98-3.11.
Sources -- Brazil and a few other locations. A good collector's stone, especially in larger sizes or darker colors.