Mg abundance of the stars. Kinematically selected Sequoia stars are plotted with blue symbols and color-coded according to their orbital energy (see Fig. 1). The measurement uncertainty and the covariance between [Mg/Fe] and [Fe/H] are indicated by the error ellipses. The data point circled with a black hexagon from R 17 indicates the abundance of HIP 28104. The abundance of the comparison samples comes from Nissen & Schuster (2010, 2011), and Reggiani et al. (2017). Filled symbols are for kinematically-selected Gaia-Enceladus stars among the comparison.