Sand

Sand

Sand isn’t a boring material if you know what you are looking at!

highly rounded sand from the Gobi Desert

Highly rounded sand grains from the Gobi Desert of Mongolia. Wind-blown sand sustains repeated tiny impacts as it bounces along Earth’s surface. These impacts gradually abrade sharp protrusions from the grains and give their surface a “frosted” luster. The width of this view is approximately 10 millimeters. Photograph by Siim Sepp, used here under a Creative Commons License.

 

Thinking About Sand

Sand is a common material found on beaches, deserts, stream banks and other landscapes worldwide. In the mind of most people, sand is a white or tan, fine-grained, granular material. However, sand is much more diverse – even beyond the pink sand beaches of Bermuda or the black sand beaches of Hawaii. These are just a few of the many types of sand.

What is Sand?

The word “sand” is actually used for a “particle size” rather than for a “material.” Sand is a loose, granular material with particles that range in size between 1/16 millimeter and 2 millimeters in diameter. It can be composed of mineral material such as quartz,orthoclase or gypsum; organic material such as mollusk shells, coral fragments or radiolarian tests; or rock fragments such asbasalt, pumice or chert. Where sand accumulates in large quantities, it can be lithified into a sedimentary rock known assandstone.

“Sand Size” Illustration

sand size

This photograph illustrates the size range of sand. The small tan sand grains in this photo are of a fine-grained sand from Qafsah, Tunisia. They are about 1/16 millimeter in diameter – the lower limit for a grain to be called “sand size.” The large brown grain is from near Worthing, England. It is a grain of coarse sand about 2 millimeters in diameter – the upper limit for a grain to be called “sand size.” Although sand particles are all tiny in size, there is an enormous relative size range between the smallest and largest. Public domain photo by Renee1137.

Most sands form when rock materials are broken down by weathering and transported by a stream to their place of deposition. A few types form when the shell or skeletal materials of organisms are broken up and transported. A few rare sands are formed chemically from materials dissolved or suspended in sea water.

Unusual Types of Sand

This page shows photos of a few types of sand that can be found worldwide. Most of the examples here are not typical. They are unusual types of sand that might only be found in a few locations worldwide. These unusual sands are a product of the types of material from which they are derived, the methods used to transport them, the chemical environment of their deposition site, and numerous other factors. After examining these photos you will probably conclude that sand can be a very diverse and interesting material.

Thanks to the many photographers who shared their photos through a Creative Commons License. Please see an attribution in the caption of each photo. A person would have to travel the world to get a collection of photos like this.

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