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Nature 392, 650-653 (16 April 1998) | doi:10.1038/33531

Mantle mineralogy:  Olivine emerges from isolation

Craig R. Bina1

Near a depth of 410 km, the speeds at which seismic waves travel in Earth's mantle rise sharply, an observation long attributed to high-pressure transformation of the mineral olivine to wadsleyite. However, seismological studies of this '410-km discontinuity' reveal wave-speed increases that are smaller and more abrupt than expected from extrapolation of the laboratory behaviour of these minerals to mantle conditions.