Grossular Garnet (Hessonite & Tsavorite)

1. Chemical Composition Calcium Aluminium Silicate - Ca3Al2(SiO4)3
2. Colors / Varieties
  • Hessonite: orange-red, brownish red, orange-yellow
  • Tsavorite (Transparent Green Grossular): green
  • Massive Hydrogrossular: green, pink, white, yellow-brown
3. Hardness 7
4. Specific Gravity 3.40 - 3.78
5. Refractive Index / Birefringence 1.730 - 1.760
6. Dispersion 0.028
7. Magnification
  • Hessonite: Heat wave effect, transparent rounded crystals, fluid inclusions
  • Tsavorite: Liquid and crystal inclusions
  • Massive Hydrogrossular: Black crystals (chromite), fingerprints
8. U.V. Fluorescence
  • Colorless to light green: Inert to weak orange in longwave and yellow orange in shortwave.
  • Yellow: Inert to weak orange in both longwave and shortwave.
9. Cause of Color
  • Green: Vanadium and / or Chromium
  • Yellow, brown: Fe3+, Mn
10. Spectrum Not characteristic
11. Treatment (Enhancement) -
12. Specific Tests & Remarks
  • Hessonite: Heat wave effect.
  • Hydrogrossular: black inclusions, may contain Idocrase intergrown in the structure
13. Simulants (with key separation tests)
14. Sources
  • Hessonite: Sri Lanka, Myanmar (Burma), Madagascar
  • Tsavorite: Kenya, Tanzania, Pakistan
  • Hydrogrossular: South Africa, New Zealand, U.S.A. (Utah, Alaska), Pakistan
15. Cuts & Uses Facetted, cabochon, beads, carvings, etc.