Bead Geyser is named after its large number of "beads," or pisolites, small, round formations of sinter. Sinter is formed as silica precipitates out of the erupting water. When the geyser erupts, the pisolites roll around in the turbulent water. After the eruption ends, water on the pisolites evaporates, leaving a new layer of silica precipitated on the rock.

This is a thin section of a pisolite. A thin section is a very thin slice of a rock which geologists can look through under a microscope. Thin sections give geologists clues to how a rock formed by letting them study minerals and structures within the rock. In this thin section, you can see concentric "rings" within the pisolite. These concentric rings suggest that they formed as the pisolite rolled around the geyser crater during eruptions.