Relaxing on Green Sandy Beaches
What better way to escape than to travel to Hawai'i and kick off our shoes on a green sandy beach?
Green beaches are pretty rare; in fact, there are only four of them in the world. They're formed by olivine crystals that have eroded from cinder cones. For example, Papakolea beach in Hawai'i is composed of eroded olivine particles from a 49,000 year old cinder cone. Olivine is created when basalt lava is high in magnesium and iron. These two elements are rather heavy for sand, so they are left behind when other sand particles are carried away by waves, leaving green beaches. Olivine is very common in the mantle of the earth and throughout space. When Apollo 15 returned to earth they brought back a sample of lunar olivine. In addition, weathered olivine on Mars might be an indication that there was once water on the planet; olivine weathers quickly, leaving idingsite, a combination of clay minerals, iron oxides and ferrihydrites
Because olivine is so prevalent in Hawaiian lavas and because olivine is one of the first crystals to form as magma cools, it is often considered the "Hawaiian Diamond". When olivine is at its finest (or most pure), it forms the gem we call peridot.
Further reading: https://www.facebook.com/TheEarthStory/posts/511311338929915 Further reading on peridot:https://www.facebook.com/TheEarthStory/posts/555689177825464 Further reading: http://www.geologyin.com/2014/11/the-green-sand-beach-mahana-beach.html Picture of Papakolea Beach courtesy of: jonny-mthttp://commons.wikimedia.org/wiki/File:Papakolea_snapshot.jpg Olivine sand grain picture: photo © Brian W. Schallerhttp://en.wikipedia.org/wiki/File:A178,_Hawaii,_USA,_Papakolea_Green_Sand_Beach,_handful_of_sand,_2007.JPG
-Colter
