Three natural olivines with Fo80Fa20, Fo71Fa29, and Fo62Fa38 compositions were investigated in situ at high pressure by single-crystal X-ray diffraction using a diamond-anvil cell up to ~8 GPa at room temperature. The bulk modulus, KT0, and its first pressure derivative, K′, do not show any significant variation among the compositions investigated and, using the data on a further sample with Fo92Fa8 composition recently investigated in the same laboratory and using the same experimental technique, we obtain, for the first time, a single equation of state for the entire Fo92Fa8-Fo62Fa38 compositional range. The equation has the following coefficients: KT0 = 124.7(9) GPa and K′ = 5.3(3) and can be used for thermodynamic calculations involving the most common mantle olivine compositions.

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