Colored Sand Beaches

From GeoClasses

1 Summary
2 The Common Tan/Beige Sanded Beach
3 The White Sanded Beach
4 The Pink Sanded Beach
5 The Purple Sanded Beach
6 The Black Sanded Beach
7 The Red Sanded Beach
8 The Green Sanded Beach
9 Rainbow Beach, Australia
10 Conclusion
11 References

Summary

My project will be over the uncommon coloring of beaches around the world. First, I will talk about the most common tan and white sand beaches and how they are formed. Then I will go on to explain to you the differences in the formation and make-up of the various other types of sand beaches. There are pink sand beaches, purple sand beaches, black sand beaches, red sand beaches, green sand beaches, and a "rainbow beach" in Australia. I will go over how they are formed and some of the geological features associated with these beaches.

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The Common Tan/Beige Sanded Beach

Common Tan Beach

Overview

Sand is a naturally occurring fine grained material composed of rock and mineral particles. The most common material that sand is made of is silica, and more specifically, quartz. The reason that quartz is so prevalent is that it is considerably hard and is very resistant to weathering. Long after most rocks and minerals are completely eroded away, quartz will remain. The rocks, minerals and quartz are transported by wind and water to the beach. The formation of the beach occurs by reworking or depositing of sediments, or by the transport of the materials by current or waves. The local rocks and minerals that arrive at the beach effect the shade of the beach. This means that the shade of tan or beige depends on the rock and mineral content of the surrounding land.

Composition

The composition of tan and beige sand is highly variable, depending on the local rock sources and conditions. The type of compositions do consist of silicates, rocks, and minerals.

Where You Can Find Them

Beaches are geological landforms that are found along a shoreline of a body of water. Beaches are most widely associated with coastal areas, but they can also form along lakes or rivers. Tan and beige colored sand beaches can be found all over the planet and are not restricted to any particular area.

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The White Sanded Beach

Whitehaven Beach, Australia

Overview

White Sand Beaches are formed in the same way that tan or beige sanded beaches. The main difference is that these beaches are almost wholly comprised of quartz. The Emerald Coast in the panhandle of Florida has great examples of white sand beaches. The quartz from the Appalation mountain range is transported to this coast. As you get closer to the Mississippi River delta though, the beaches grow to be more of a crème than a white. The reason is that the Mississippi is able to carry a slightly more varied array of rocks and minerals than in other areas of the Emerald coast. There are other areas in the world that have white sand beaches as well, and for the most part, they are in very quartz rich areas.

Composition

The composition of white sand is mostly quartz. The type of compositions do consist of other silicates, rocks, and minerals, but sometimes as little as 1%.

Where You Can Find Them

Coastal areas which are very rich in quartz. Also, some areas can receive the quartz by weathering of a different area and are transported somehow to that coast. Some examples are:

The Emerald Coast, Florida
Whitehaven Inlet, Australia
Bahamas
Mediteranean

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The Pink Sanded Beach

Pink Sand Beach, Bahamas

Overview

Pink Sand beaches only occur in areas with a very large coral reef formation somewhere close. The reason for this is because of the main ingredient for a pink sand beach. This ingredient is weathered coral and shell fragments. Not all coastlines near large reef systems have the characteristic of pink sand. The reefs must contain an organism called Homotrema rubrum. There is no common name for them, but they are a forminifera that have a red skeleton. When they die, the skeletons of the creature fall to the ocean floor. The remains are then taken by the current to the shore, and they are slowly eroded as they travel to the beach. By the time they are deposited onto the actual shoreline, they are small particles that mix in with the sand.

Composition

The sand of these pink beaches are made up of silicates just like the more common tan, beige, and white beaches. The only difference is the coral or skeleton of the Homotrema Rubrum.

Where You Can Find Them

Pink sand beaches can be found in:

The Caribbean (Bahamas, Puerto Rico, Bermuda, Barbados)
The Phillipines
Scotland

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The Purple Sanded Beach

Purple Sand on Beach

Overview

Sometimes, coastal areas will be rich in minerals of almandine and/or garnet. When the wind and weather erode the landscape that contains the almandine and garnet, it will produce purple sand. It is not common, but it is seen in at least 2 places. In central California, in Big Sur, there is Pfeiffer beach. The hillsides that surround the beach are full of maganese garnet. The garnet gets washed down to the beaches to turn the sand a purple color. Also, the mountains northwest of Long Island carry the mineral piedmontite which has turned the coastal sands purple as well. The photograph below is of piedmontite, and you can see the vivid purple hue.

Garnet

Composition

The sand on in Big Sur and on Long Island all have various silicates, rocks, and minerals. The sand from Pfeiffer beach in Big Sur is colored by the addition of maganese almandine and maganese garnet. The beaches of Long Island are colored by piedmontite from the mountains in the northwest.

Where You Can Find Them

Big Sur, Central California
Long Island, New York

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The Black Sanded Beach

Black Sand Beach, Hawaii

Overview

Black sand beaches result from having volcanic activity near a coastline. The activity could have been many centuries past or can still be active. The actual particles are made up of basalt. Cooled lava flows or pillow basalts are eroded to create the beaches. The sand on the beaches with current volcanic activity can constantly become covered by new lava flows.

Basaltic Lava Flow

These beaches are considered more of a coastline than an actual beach, but the reminants of that type of shoreline will eventually create a black sand. The beaches that have not had volcanic activity in an extensive period of time have fine, polished granules of basalt as sand. This basalt is what creates the black color of the beach.

Composition

Black sand beaches are made of cooled and weathered lava. Depending on the composition of the lava, these beaches can have a wide variety of rocks and minerals. The main ingredient would be basalt and silicates. There also may be magnetite’s and the rock gabbro. Metals such as iron, titanium, tungsten, zirconium, and thorium may also appear within these beaches. Many gemstones form within volcanoes or volcanic rock and may show up in these sands. Gemstones such as garnets, rubies, sapphires, topaz, and, of course, diamonds.

Where You Can Find Them

You can usually find a black sand beach when there is or was volcanic activity. Some of these are:

Hawaiian Islands
Patagonia
Albay, Tahiti, Fiji in the Phillipines
California
Santorini, Greece
Dominican Republic

Punalu'u Black Sand Beach, Hawaii

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The Red Sanded Beach

Kaihalulu Beach, Hawaii

Overview

Red sand beaches are less common than black sand beaches, but have many of the same characteristics. In order to have a red sand beach, you must have a coastline that is very close to a previously active volcano. This sand is not formed from the erosion of the cooled basaltic lava, but from the erosion of the cinder cone of the volcano. The cinder cones that surround the red sand beaches are made up of iron and hematite. The red pigment of the sand is created from the oxidation of the iron and the reddish color of the hematite. Some black basaltic sand is also mixed in, which gives the beaches a very dark red color. These beaches only form when there is minimal erosion of the sand particles into the ocean. The particles are very easily washed away, which makes it difficult to keep a red sand beach from disappearing. As you can see from the photographs, rocks are breaking the waves that would most likely wash the beach out to sea.

Composition

Red sand beaches are made of:

Iron
Hematite
Basalt
Silicates
Mafic Minerals

Where You Can Find Them

There are red sand beaches in:

Hawaii
Crete
Santorini, Greece

Red Beach, Santorini, Greece

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The Green Sanded Beach

Green Sand Beach, Hawaii

Overview

Green sand beaches are literally a gem of a find. The beaches are formed when basaltic lava has large quantities of olivine in them. Olivine is a green mafic mineral that can form the gemstone peridot. The beaches have a very high wave current, which helps erode the olivine from the mafic lava. Also, olivine is heavier than other silicates and sands. When the strong wave energy pounds against the coast, the olivine stays put while the other sand particles are swept out to sea. This is why the beach is such a pure green color. Many visitors have actually found large peridots on the beach, large enough to sell to jewelers.

Sand from Pu'u Mahana Beach, Hawaii

Peridot and Basaltic Rock

Composition

Due to the power of the current and waves hitting the beach, the sands are almost wholly comprised of olivine. The other particles in the sand consist of basalt, mafic minerals, silicates, and iron.

Where You Can Find Them

Hawaii
Galapagos Islands
Guam

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Rainbow Beach, Australia

Rainbow Beach Sand Dunes, Australia

Overview

Rainbow beach is located on Fraser Island in Australia. This island is unique in that it is home to over 70 different types and colors of sand. This has the most coastal variety of sand than anywhere else in the world. The beach is a huge mesh of the many different sands located on the island. The mixture turns the sand into a vibrant orange color. The dunes have been said to look like layers of rainbow sherbert.

Rainbow Beach Sand Dune, Australia

Much of the sand colors come from the rich content of minerals in the sand. There is no known cause for these multicolored dunes, but they are believed to have started forming somewhere around the last ice age.

Tourist on Orange Sand, Rainbow Beach, Australia

Composition

rutile
ilmenite
zircon
monazite
ilminite
silicates
quartz

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Conclusion

Beaches are essentially made from the same process: The weathering of land. Most beaches are either tan, beige, or white in color, and generally are made up of common silicates, rocks, minerals, and quartz. Just a slight variation in the content of the sand or the land that is being weathered can create beaches in a wide array of colors. Some of these are vary rare and hard to find, but all of them are beautiful. Now that you know more about how they are made, and what they are made of, I hope you find them not only beautiful, but interesting as well.

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