Gold is typically found in placer deposits, which are formed when the mineral is transported by rivers or streams and deposited in the riverbed. Gold is a heavy mineral, so it tends to settle out of the water and collect in areas where the water flow is slower or where there are obstacles that trap the gold. Some of the gold becomes trapped in crevices and cracks in the bedrock, while other gold particles may be mixed in with the riverbed sediments. Over time, the gold can become covered by other sediments, such as sand, gravel, and mud.