Figure 4: Observed (cross), calculated (red line) and difference (blue line) XRD patterns for the Rietveld refinement of the sample.
From: New silica clathrate minerals that are isostructural with natural gas hydrates

(a) The entire region. (b) Enlarged view of low-angle part. The tick marks represent the calculated peak positions for chibaite (green), the DOH-type mineral (orange) and quartz (purple), in descending order. The arrows in b show diffraction peaks from the DOH-type mineral.