Evolution of low-k X-ray scattering from MgSiO₃ as a function of annealing temperature. Three features at ~1.4, ~1.8 and ~2.5 Å^-1 labelled XA, XB and XC are present below the limiting scattering vector magnitude of ~2.5 Å^-1 for sampling medium-range structure. Patterns for each sample are offset in y-axis direction for clarity.