“Thin section showing quartz-filled fracture in chert and vugs also filled by void-filling quartz. There are also silt-sized quartz grains “floating” in cherty matrix. At lower right is a layer of silty to clayey material (referring to size grade) that separates two major vugs. The chert is secondary, having replaced a rock dominated by a carbonate (limestone or dolostone). Thin section and photograph by Norman King from sample collected by Phil Richardson and now in collection of Norman King.”