pollucite

…Earth’s crust in the minerals pollucite, rhodizite, and lepidolite. Pollucite (Cs₄Al₄Si₉O₂₆∙H₂O) is a cesium-rich mineral resembling quartz. It contains 40.1 percent cesium on a pure basis, and impure samples are ordinarily separated by hand-sorting methods to greater than 25 percent cesium. Large pollucite deposits have been found in Zimbabwe and…