Why do some beaches in Hawaii have black, green, gray, or red sand?
In Hawaii there are white sand, black sand, gray sand, green sand, and red sand beaches, but not all types of sand are found on each island. The color depends what the sand was created from. In Hawaii the term black sand beach is used only for beaches with a high concentration of grains of black volcanic glass. The black volcanic glass is created by molten lava flows entering the cool ocean causing the glassy rinds to shatter. True black sand beaches are only found in a few locations on the Big Island. There are beaches on the Big Island and the other Hawaiian Islands that appear black in color but they only have a small percent, a small pocket, or trace amounts of black volcanic glass and they are not true black sand beaches. Green sand beaches are created from grains of a semi-precious gem called olivine. White sand beaches are created from bits of shells, calcareous algae, sea urchins, and coral. Gray sand beaches are created from gray basalt. Red sand beaches are created from grain
