Nickel is an abundant element in the bulk earth, and nickel-dominant olivine, liebenbergite, is the only igneous nickel-rich silicate found in nature. In this study, we used high-pressure single-crystal diffraction to explore the compressional behavior of a synthetic liebenbergite sample up to 42.6 GPa at ambient temperature. Over the studied pressure range, the liebenbergite sample retains the orthorhombic Pbnm structure, and no phase transition is observed. A third-order Birch-Murnaghan equation of state was used to fit the pressure behavior of the unit-cell volume, lattice parameters, the polyhedral volume, and the average bond length within each polyhedron. The best-fit bulk modulus K-T0 = 163(3) GPa and its pressure derivative K-T0' = 4.5(3). We find that liebenbergite is the most incompressible olivine-group silicate reported thus far, and Ni2+ tends to increase the isothermal bulk modulus of both olivine-and spinel-structured silicates. Consequently, Ni-rich olivine has a higher density compared to Ni-poor olivine at the upper mantle P-T conditions; however enrichment of Ni in mantle olivine is generally too low to make this density difference relevant for fractionation or buoyancy. Publication name | AMERICAN MINERALOGIST, 104 (4):580-587; 10.2138/am-2019-6680 APR 2019 | Author(s) | Zhang, Dongzhou; Hu, Yi; Xu, Jingui; Downs, Robert T.; Hammer, Julia E.; Dera, Przemyslaw K. | Corresponding author(s) | ZHANG Dongzhou dzhang@hawaii.edu Univ Hawaii Manoa, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA. Univ Chicago, GeoSoilEnviroCARS, Lemont, IL 60439 USA. | Author(s) from IGCAS | XU Jingui | View here for the details
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