One of only a handful of green-sand beaches on Earth, at the southern tip of the Big Island of Hawaii, the southernmost point of the United States. The green is olivine, the gem peridot, eroded from a cinder cone and too heavy to wash away, so it collects in a pocket of the black lava while the lighter sand goes to sea. It is a hard hike or a bumpy ride to reach it. Look, do not take: removing the sand is prohibited, and Hawaiians ask that you leave the land as you found it.
Olivine (peridot)
See it on the map
Other places on the map within a couple of hours.