Ultramafic rocks like peridotite consist of pyroxene and this mineral.
The 410 kilometer seismic discontinuity in the mantle results from this mineral's transformation to spinel. This mineral occurs as a solid solution of forsterite and fayalite. According to Goldich's stability series, this mineral and the calcium plagiocase anorthite are most easily weathered. 500 Celsius is the boundary temperature for a reversible reaction in which this mineral and water combine to yield serpentine. Ultramafic rocks like peridotite consist of pyroxene and this mineral. This mineral consists of silica tetrahedra linked by magnesium or iron cations. For 10 points, name this mineral at the top of the discontinuous branch of Bowen's reaction series.
The 410 kilometer seismic discontinuity in the mantle results from this mineral's transformation to spinel.
olivine