It contains glassy olivine crystals which are washed out of basalt lava flows by the ocean. This photo has been taken near Papakolea Green Sand Beach, Hawaii. Green sand beaches are rare.
There were only a hand full people at the Queen’s Bath near Kiholo Bay. One of them was Autumn. She shot some Polaroids and gave me this one. The Queen’s bath is a lava tube in the woods near the beach flooded with fresh water. It was Autumn’s birthday. And of course it’s autumn in Hawaii.