
Beach sand isn't necessarily made from the same material everywhere. Its color can come from minerals, volcanic rock, coral fragments, shells, and other materials that have been broken down over time.
Black sand, for example, can contain large amounts of dark volcanic minerals. White sand may contain abundant fragments of coral or other pale materials.
This means the appearance of a beach can provide clues about the geology and organisms surrounding it. A beach's sand is essentially a collection of tiny pieces of its environment.
© U.S. Geological Survey
