| SiO2 (wt%) | 0.05 | 0.07 | 0.09 | 0.07 |
| TiO2 | 0.12 | 0.13 | 0.13 | 0.11 |
| Al2O3 | 57.82 | 57.84 | 57.50 | 57.40 |
| Cr2O3 | 10.39 | 10.26 | 10.41 | 10.40 |
| FeOt | 10.25 | 10.17 | 10.37 | 10.18 |
| MnO | 0.13 | 0.08 | 0.09 | 0.06 |
| MgO | 21.20 | 21.40 | 21.06 | 21.02 |
| CaO | 0.00 | 0.00 | 0.00 | 0.00 |
| NiO | 0.36 | 0.35 | 0.29 | 0.33 |
| V2O5 | 0.00 | 0.05 | 0.01 | 0.00 |
| Sum | 100.31 | 100.35 | 99.94 | 99.58 |
| Fe2O3 (calc) | 1.88 | 1.91 | 1.77 | 1.71 |
| FeO (calc) | 8.55 | 8.45 | 8.78 | 8.64 |
| Sum (calc.) | 100.50 | 100.54 | 100.12 | 99.75 |
| Si (a.p.f.u.) | 0.010 | 0.014 | 0.018 | 0.015 |
| Ti | 0.018 | 0.021 | 0.019 | 0.017 |
| Al | 13.971 | 13.954 | 13.953 | 13.971 |
| Cr | 1.684 | 1.661 | 1.694 | 1.698 |
| Fe3+ | 0.290 | 0.295 | 0.275 | 0.266 |
| Fe2+ | 1.466 | 1.447 | 1.511 | 1.492 |
| Mn | 0.022 | 0.014 | 0.016 | 0.011 |
| Mg | 6.479 | 6.530 | 6.464 | 6.473 |
| Ca | 0.001 | 0.000 | 0.000 | 0.001 |
| Na | 0.000 | 0.000 | 0.000 | 0.000 |
| Ni | 0.059 | 0.058 | 0.048 | 0.055 |
| V2O5 | 0.000 | 0.007 | 0.001 | 0.000 |
| Mg# | 81.5 | 81.9 | 81.1 | 81.3 |
| Cr# | 10.8 | 10.6 | 10.8 | 10.8 |