Smooth rocks that you find along riverbanks and other bodies of water did not start out that way. In nature, a rock’s rough edges are polished away over a long period of time as water and sand or gravel repeatedly washes over it to reveal inner colors and composition. By mimicking this natural weathering process, this Rock Tumbler can turn rough-edged rocks into smooth shiny stones showcasing intriguing colors and patterns in a matter of 2 to 4 weeks. Junior geologists will love seeing the everyday rocks they’ve collected transformed into shiny works of art and exploring how different types of stones and different tumbling conditions can yield unusual results.