Rietveld plot for the refinement of Na3(C6H5O7). The red crosses represent the observed data points, and the green line is the calculated pattern. The magenta curve is the difference pattern, plotted at the same scale as the other patterns. The vertical scale has been multiplied by a factor of 5 for 2θ > 12.8°. The lower row of black tick marks indicates the reflection positions for the major phase and the upper row of red tick marks is for the dihydrate impurity.