Color -- Colorless to light pink, yellow, or brown.
Optics -- R.I. 1.64-1.67. Biaxial negative.
Durability -- Hardness 5.
Crystal structure -- Monoclinic.
Specific Gravity -- 3.05-3.08.
Sources -- Quite rare. While traces are found in several widely scattered locations, only Brazil has produced cuttable specimens, which are usually only a carat or two in size.