Sand under a Microscope, Magnified 250 Times
Adam Rifkin stashed this in Images!
Most sand is tiny, tiny rocks mixed with shells like this. The ratio of rocks and coral to shells differs depending on the beach you are at.
For obvious reasons, deserts almost never have the tiny shells.
But so colorful and varied? Wow.
Grains of sand all seem so similar to the naked eye.
Sand at 250x is beautiful: http://www.lostateminor.com/2011/07/12/tiny-grains-of-sand-magnified-to-250-times-real-size/