- Figure 18 X-ray powder diffraction profile of the clay fraction of soil collected from within the lead pipe. Peaks are labeled according to the crystallographic d-spacings that they represent (in nm). The different saturations/treatments of the clay are performed to elicit changes in the structures of the clay minerals. The occurrence of mica in the soil clay is validated by the 1.0 nm peak in the K+-saturated, 25°C treatmen. The presence of smectite is confirmed by the 1.2 nm peak in the K+-saturated, 25°C treatment and the 1.7 nm peak in the Mg2+-saturated, glycerol treatment. Other minerals found in the clay fraction include: quartz (0.42 nm and 0.34 nm peaks), calcite (0.3 nm peak), and cerrusite (0.36 nm peak).
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