Olivine Beach on Big Hawaii

June 06, 2005


Provided by: Ray Pavlik, CCHS Earth Science
Summary authors & editors: Ray Pavlik; Steve Mattox

The photo above showing an olivine beach was taken on April 18, 2005 from near South Point, on the Big Island of Hawaii. Olivine is common in basalt lava. Green Sand Beach was formed by erosion and a high concentration of olivine crystals derived from the Puu Mahana volcanic cone. Puu Mahana is a tuff ring, which is a type of volcano formed by the interaction of magma and shallow groundwater. The cone is associated with the Southwest Rift Zone of Mauna Loa, however, the cone doesn't sit directly on the rift. Mauna Loa flows can contain abundant olivine crystals. As ocean waves crashed against the coast they eventually wore away the cone and created a small bay. The waves also removed the lighter grains of sand (made of volcanic ash), leaving behind the denser olivine crystals.

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