Spring! Things get warmer and wetter. “April showers bring May flowers.” But rain showers also bring mud!
Mud is the toy of children and bane of adults. Mud dirties our cars, stains our clothes, and forces us to clean our dogs before we bring them inside. But there’s another aspect to mud too. The most important ingredient in mud is clay. And clay might be the most important mineral in human history!
Clays are minerals? Yes! Clay is basically an aluminum silicate (technically a phyllosilicate) with bonded water attached. Of course, there are variations from kaolinite to montmorillonite, from smectite to illite. Incidentally, kaolinite is the famous source of porcelain. Clay crystals are very small, about 0.7 microns in diameter and 0.005 microns in thickness (one micron is 1/25,000th of an inch).
Basically, clay is a flake - very wide and very thin - whose sides are electrically charged. That electric charge attracts water, which is what turns clay into a very slimy mud. But it also gives clay its plasticity; it’s ability to be molded into a mind-boggling array of shapes.
Before the Iron Age, before the Bronze Age, humankind’s first step towards civilization began with clay. Ancient tribes and peoples began making idols and pottery at least as early as 12,000 years ago. Thanks to clay pottery, humans learned to cook foods like soups and stews, which not only broadened our palate, but allowed humans to ingest the previously unavailable nutrition of cereals like barley and maize. Clay pottery made cooking (and with it, cereal agriculture) worthwhile. And if you leave a barley-water mixture unattended for a while, you get beer! And so pottery allowed humans their first constructive use of chemistry in the form of viniculture.
Clay was used to form bricks, stucco and tiles. Permanent walled structures were built. Cities were born. Metallurgy may have been born in a potter’s kiln. How? Thanks to the high temperatures and oxidation processes in pottery kilns, brightly colored oxide pottery finishes (think green malachite or bright blue azurite) would yield refined metals like copper. Smelting was born, and with smelting came the Bronze Age. The first written words of history were recorded on clay tablets.
So thanks to clay, humans took their first steps in the sciences of cooking, chemistry, metallurgy, city-building, and the written word.
Clay influences our lives to this day. Clay is used for the cups we drink from, the dishes we eat from, the tile we walk on, and the toilets we sit on. But clay is also used for paper and rubber production, cosmetics manufacturing, petroleum exploration and certain medicines.
According to the USGS’s Mineral Commodity Survey 2016, America produced over 25 million tons of clay from 150 companies in 40 states worth a total of $1.5 billion.
So my sympathies for parents and pet-owners who have to clean up their loved ones after a rainy day. But playing with mud is how civilization began!
United States, United States Geological Survey. Mineral Commodity Survey: Clays, 2016. USGS, Jan. 2016. minerals.usgs.gov/minerals/pubs/commodity/clays/mcs-2016-clays.pdf. Accessed 23 Jan. 2017.
Staubach, Suzanne. Clay: The History and Evolution of Humankind’s Relationship with Earth’s Most Primal Element. New York: Berkley Books, 2005.
Prinz, Martin, George Harlow, and Joseph Peters (Eds). Simon and Schuster’s Guide to Rocks & Minerals. 78th ed. New York: Simon and Schuster, 1978.
Heath Shive is a freelance writer and former geologist. His articles have won regional and national awards. His favorite hobby is to read any book put in front of him. His second favorite hobby is writing about what he reads.
Hello! My name is Heath Shive, content manager at ScholarFox. I'll be the author of most of the blog posts. I'm a former geologist and currently a freelance writer. The world is complex and seemingly crazy. Good! Because when you love to learn, you'll never be bored.