Pu’u o Mahana, or Papakolea Beach (Green Sand), is the spectacular erosion product of a volcanic cinder cone near South Point on the Big Island of Hawaii. It can be reached through a 1-hour hike going through some beautiful scenics. The unusual color of green sand stems from the semi-precious stone olivine, polished over time by the action of waves. The crystals of olivine form in abundance when hot volcanic lava cools down. Since this mineral is much harder than the surrounding lava matrix, it tends to accumulate over time near areas of lava erosion.