Microscopy Image Gallery


Exploration of the Month

February 1999


At this time of the year it is always nice to think of somewhere warm.
What better place could there be than lying in the hot sun at the beach! This month we take a closer look at sand.

CA Beach sand CT Beach sand

There are many different sorts of beach sand, so many in fact that it may be possible to identify a sample of sand as coming from a particular beach anywhere in the world. The images on this page show sand from diferent places to highlight some of these differences. The two images above show sand from opposite sides of the United States. The sand on the left is from a beach in California, the sand on the right comes from Connecticut. Notice how different the individual grains look. The California grains are smooth and rounded, but those from Connecticut are rough and angular. Can you pick out some similarities between the two sets of sand?

FL Beach sand FL Beach sand

Most sand starts out life as rock, maybe a piece of a mountain somewhere. It is broken down by the forces of nature - wind, rain, river water, frost, sunlight and so on. Eventually, all that remains of the piece of mountain are the tiny grains we call sand. In these two pictures here (and the two above) you can see that there are different colored grains, and grains with different texture. Some of the different colors are because the grains are differnet minerals. The clear grains ase quartz. Other grains are the remnants of broken shells. The two images here are from the Gulf and Atlantic coasts of Florida, and are largely quartz grains with some shell fragments. The small black particle in the left image is the remains of a fossil, which forms part of the sand grains at Venice beach FL.

The sand grains shown here are all between 0.05 mm and 2 mm in size, which is how geologists define sand. Larger grains form gravel, and smaller ones are called silt.

Cancun Beach sand Gulf of Mexico sand White Sands NM sand

Beuatiful beaches are often chatacterized as having lots of pure, white sand. However, there are different sorts of white sand, as these three images show. The first image shows sand from Cancun, Mexico. It is formed of glossy, creamy colored likmestone grains. On the other side of the Gulf of Mexico a sand bar off the coast of Florida shows grains that are entirely composed of quartz. The third image also shows white crystal grains, this time from the desert of New Mexico. Notice how the desert wind has resulted in a different character from the grains on the beach. They are more angular and rough-looking rather than the more smoothly polished appearance of the beach sand.


Nebraska river sand Mt. St. Helens ash Hawaii volcanic sand

Sand may also be found away from beaches and deserts. Here are three different examples of sand. The first is river sand from the Platte river in Nebraska. Eventually the sand will be washed down river to the sea, and form part of the coastal beach. The second image shows even younger sand, in this case a sample of ash from the eruption of Mt. St. Helens in Washington. Notice how the grains have not yet been rounded off or polished. The last image demonstrates that sand does not have to be white. It is a black volcanic glass sand from the island of Hawaii.


See what sort of sand you can find around you.


Other Explorations


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Last Update: 2/26/99