A specialty from the many-colored tourmaline group with excellent qualities and good hardness. Tiny traces of chrome give it that fine hue, similar to that of an emerald.
Formula: Na(Li, Al)3Al6B3Si6O27(OH)3(OH,F)
Hardness: 7 – 7.5
Density: 2.90 – 3.40 g/cm3
Refractive Index: 1.614 – 1.666 DR: 0.014 – 0.032
Color: Green
Countries of Origin: Tanzania
Birthstone: October