The white and gray colors surrounding the crater of Bead Geyser are deposits of siliceous sinter. Silica disolves into the water in heated reservoirs deep below the surface. When the geyser erupts, the erupting water splashes back down onto the geyser crater. As this water cools and evaporates, silica precipitates out of the water and accumulates around the geyser as sinter.

Sinter formations form very slowly, sometimes only 1/100 of an inch per year. The sinter deposits take on all sorts of shapes; some are wafer-thin layers that form the rim; others are large, like the mounds surrounding the vent of Bead Geyser. Still others are small and round like beads. Also called pisolites, the sinter beads give Bead Geyser its name.

This picture on the left shows a knobby sinter structure that grew in the geyser crater around Bead Geyser. The picture on the right is a thin section of a similar knobby structure and shows the internal layers of sinter that make up the structure.