In The Loupe  |  The Microscope.com Blog

Apr/13

22

5 FACTS ABOUT SAND

For many of us sand is something we warm our toes in on the beach or play with under the climbing frame in the yard. It is yellow, small, gritty and is trailed throughout the house.Yet when looked at under a high power, compound microscope, it is transformed into a myriad of different shapes and sizes and an equal number of colors of breathtaking beauty.  Dr Gary Greenberg has spent a lifetime studying sand and collecting a library of images through a microscope. Here are five interesting facts from his book  A Grain of Sand:

1.       Sand Signature: Forensic scientists can determine exactly where a particular sand originated. In World War II, the Japanese sent over 9,000 balloon bombs to drift over the Pacific Ocean in order to bomb the US. 320 landed in Oregon, Montana and Wyoming with one actually killing six people – the only combat casualties in the continental US. US scientists subsequently pinpointed the bomb factory by analyzing the sand contained in the balloons’ ballast sandbags. Since the sand had no quartz or granite crystals typical of a continent, they surmised the sand came from an island, in this case, Japan. Second, it contained coral so was likely from north of the tropical 35th parallel. Third, and the clincher, the sand contained a rare diatom discovered by a French expedition in 1889 and only found in an area near Tokyo.  The US ended balloon bombs with their own bombing raid.

 2.       Stars > Grains of Sand: This is hard to believe but the astronomer Carl Sagan was probably right that the number of stars outnumbers the grains of sand on the world’s beaches. Based on certain assumptions about average grain size, beach depth and length, one estimate puts the number of grains of sand at 4,800,000,000,000,000,000,000. While we can only see about 6,000 stars at night in our galaxy, the Hubble Space telescope indicates the universe contains about 130 billion galaxies. The average galaxy contains about 400,000,000,000 stars, which indicates a total of 52,000,000,000,000,000,000,000 stars! Of course, once you count the sands of the desert, it may be a different story!

3.      Singing Sands: Speaking of deserts, some people have heard eerie sounds coming from sand, like a freight train. They were not crazy! In specific deserts such as Eureka Dunes, CA or Sand Mountain, NV there are singing or barking sands. Characterized by specific conditions including dry and spherical sand grains, these sands emit a variety of sounds. Pitch is related to the grain size and volume to the surface texture. Of course, wind is an essential driver. Some people have had to shout in order to be heard over the singing!

4.       Size, Shape & Colors: Like us, every single grain of sand is unique. They come in an infinite variety of shapes and colors. They are not just a mass of yellowish stones. Take a look under a microscopes  and the full iridescent glory of their coloring and shapes becomes apparent. Bright reds of garnet, the pink of coral, the green of nephrite (a form of jade) and a plethora of others including of course, yellow. 

5.       Sources of Sand: In spite of these manifold differences, sand originates from only three sources:  Rocks, Organisms or Minerals. Rocks form mineral sands. Organisms form biogenic sands and Minerals form precipitated sands. That’s it. Such a simple origin for such a complex array of sands.

You can enjoy the delights of sand with any high power, compound microscope. Using 40x-400x will bring the individual grains of sand into sharp contrast and while you may not be able to replicate the quality of Dr Greenberg’s images, you will never look at a beach in quite the same way again.

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