Spodumene
Spodumene with a pink or violet hue is commonly called Kunzite. If the color leans towards green, it is known as Hiddenite. Uncolored or yellowish specimens are referred to as Triphane or simply Spodumene. There are ongoing discussions about labeling it as Hiddenite. Currently, I have chosen to label anything in the green range as Hiddenite, regardless of whether the color is caused by chromium or not.
Physical properties:
| Chemistry: | LiAl[Si2O6] |
| Hardness: | 6.5-7 |
| SG: | 3.16-3.20 |
| Cleavage: | Perfect, two directions |
| Fracture: | Very brittle |
| Thermal sensitivity: | Somewhat |
Optical properties:
| RI: | 1.655-1.68 |
| Dispersion: | 0.017 (medium) |
| Birefringence: | 0.015 (medium) |
| Pleochroism: | Pronounced, trichroic |
| Critical angle: | 37° |
Facet angles (pavilion/crown):
| Vargas: | 42°/40° |
| Soukup: | 39°/43° |
| Roth: | 39°/43° |
| Hashnu: | 42°/40° |
| Sinkankas: | 40°/40° |
| GIA: | 39°/43° |
| Perkins: | 39°/43° |
| Raytech: | 40°/39° |
| Cornwall: | 42°/35° |
| Weikoff: | 42°/39° |
| Carroll: | 42.5°/35.3° |
Cutting lap:
Only fine grit (never coarser than 600)
Facet polishing:
| Vargas: | Aluminum oxide or tin oxide on tin/lead or tin |
| Soukup: | Aluminum oxide or tin oxide on tin |
| Christiansen: | Aluminum oxide or tin oxide on tin/lead or tin |
| Perkins: | Cerium oxide on BATT or Corian |
| MDR: | 14-50k diamond on zinc |
| Raytech: | Aluminum oxide on Fast Lap, tin or phenolic |
Cabochon polishing:
| Christiansen: | Aluminum oxide or 50k/100k diamond on leather or wood |
Orientation:
Best color when perpendicular to the C-axis. Angle the table facet 5-10 degrees away from the cleavage plane.
Treatments/synthetics:
Heat treatment can enhance the color. Irradiated Kunzite may fade in sunlight.
Tips!
Be patient, grinding spodumene takes time, often a long time to avoid creating stress in the stone that can later develop into cracks.
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