Here is some amazing microphotography by Dr Gary Greenberg who shows how beach sand grains look magnified to 250 times the real size.
This crystal of sand on the image below (in the middle) is surrounded by bits of coral, shell, and volcanic material.
A great deal of grains are of biologic origin. Most of us don’t think of beach sand consisting mostly of colorful shells. However, they make up most of the sand.
Leaving microphotography aside, if we had slightly better vision this is how we could see beach sand. These two photos below are made with macro lens by Niall Crotty ©