An unusual geyser formed on the bank of Iron Creek. Cliff Geyser formed a rim or wall-like ridge of sinter around its crater from which it erupts 30 to 40 feet high. The famous Handkerchief Pool was once the drawing attraction to Black Sand Basin. Convection currents then whisked their laundry away where it would reappear again at the surface, freshly laundered. Depth 6 feet.
Opalescent pool has a cooler temperature than other thermal features at Black Sand Basin.
Early in its history Opalescent was a boiling spring, surrounded by smaller springs. In the early 1950s it was a small dry pool, then the run-off from Spouter Geyser flowed into it. The increased water flow flooded the surrounding area, killing the lodgepole pine. This silica, a non-crystalline compound, slowly impregnates the wood and over time, with the absence of oxygen, could eventually petrify the wood. F Interval 1-2 hours.