Apatite
Physical Properties:
| Chemistry: | Ca5(F,Cl)(PO4)3 |
| Hardness: | 5 |
| SG: | 3.15–3.22 |
| Cleavage: | Imperfect, two directions |
| Fracture: | Brittle |
| Thermal Sensitivity: | High |
Optical Properties:
| RI: | 1.63–1.65 |
| Dispersion: | 0.016 (medium) |
| Double Refraction: | 0.004 (weak) |
| Pleochroism: | Varying (usually weak in green and strong in blue) |
| Critical Angle: | 37.5° |
Facet angles (pavilion/crown):
| Vargas: | 42°/41° |
| Olson: | 40°/43° |
| Soukup: | 39°/43° |
| Roth: | 39°/43° |
| MDR: | 39°/43° |
| Schlagel: | 39°/35° |
| Hashnu: | 42°/41° |
| Sinkankas: | 40°/40° |
| GIA: | 39°/43° |
| Perkins: | 39°/43° |
| Cornwall: | 42°/35° |
| Weikoff: | 43°/39° |
| Carroll: | 42.6°/35.3° |
Cutting lap:
Medium or fine
Facet polishing:
| Vargas: | Aluminum oxide on wax or tin/lead with low speed, Ultralap with tin oxide |
| Olson: | Tin oxide on wood or wax |
| Soukup: | Aluminum oxide on tin or tin/lead |
| Christiansen: | Aluminum oxide on vinyl, lead, or tin/lead with low speed |
| Perkins: | Aluminum oxide on BATT or Corian |
| MDR: | Tin oxide on tin or aluminum oxide on type metal |
Cabochon polishing:
| Christiansen: | Aluminum oxide on leather or felt, cerium oxide on felt |
Orienting:
Based on the best color and yield
Treatments/Synthetics:
None known
Tips!
Be careful with the high heat sensitivity, especially during dopping (use glue). The polishing characteristics are very variable. What polishes one stone may not work at all on another.
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