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How Does Sand Get Its Color?

Sand’s color is derived from its mineralogy, or the physical structure of the crystals that populate the sand.

By
Sabrina Stierwalt, PhD ,
January 29, 2018
Episode #271

Whether it’s white, black, pink, red, or even green, the color of sand provides clues as to its makeup and offers a peek into the beach’s history. The color of sand can tell stories of past human activity and can even reveal what kind of sea creatures call that beach home.

Sand’s color is derived from its mineralogy, or the physical structure of the crystals that populate the sand. These minerals can come from erosion of nearby landscape, volcanic eruptions, and even the grounding up of sea shells over decades, so the color and content of sand reflect the makeup of the surrounding landscape and even the beach’s inhabitants.

So how do sand beaches around the world get their colors? Let’s take a look at how some of the world’s most colorful beaches came to be.

What Causes Sand to Be White?

White sand beaches are some of the most striking to look at, so striking in fact you’ll need to wear sunglasses to withstand the glare. Hyams Beach in New South Wales, Australia, is on record as the whitest sand beach on Earth according to the Guiness Book of World Records. The sand owes its bright white color to the purity of its content which is mostly finely ground quartz crystals with a lack of contaminants that could dull its color. Clearwater Beach on the Florida barrier island between Tampa and the Gulf of Mexico and the beaches on Angaga Island in the Maldives also host strikingly white sand beaches composed of a finely ground powder of quartz.

What Causes Sand to Be Red?

Red sand beaches, like those that cover much of Prince Edward Island in Canada, including Cavendish Beach, derive their color from iron-rich minerals. When iron comes into contact with oxygen it forms iron oxide or what we more familiarly call rust. This oxidation leaves the minerals looking different shades of red and is the same process at work in the rust-colored, iron-rich dust on Mars.

A volcanic cinder cone, a simple, single-vent volcano, surrounds the Kaihalulu Beach in Maui supplying it with iron-rich minerals and thus red sand. Similarly, the iron-rich black and red lava rocks have produced the Kokkini Beach, known as Red Sand Beach, nestled into the base of the nearby volcanic cliffs of Santorini, Greece.

What Causes Sand to Be Orange?

Minerals high in iron can also produce sand with an orange hue as seen on the beaches of Ramla Bay in Gozo, Malta, and in Porto Covo, Portugal. Similarly, the orange sands in Porto Ferro in Sardinia, Italy, come from a combination of orange limestone, crushed shells, and volcanic deposits.

What Causes Sand to Be Pink?

When a beach has pink sand, some form of coral is usually nearby. The shade of pink usually reveals a mixture of white sand with red shells or calcium carbonate from coral and thus can range from pastel to deeper pinks. The famous pink sand beaches on Harbour Island in the Bahamas are composed of ground up foraminifera, a single-celled marine organism with a red-colored shell. The beaches in Balos, Crete, also get their pink hue from crushed shells. In Tangis Beach in Indonesia and the Rangiroa Atoll in French Polynesia, white sand is mixed with red coral to produce pink sand.

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