What’s a Diatom?

• Diatoms are microscopic algae creatures that live in oceans, seas and deep lakes.
• When they die, their hard shell-like skeletal remains fall to the lake or sea bottom.
• Their fossilized remains are made of amorphous silica with the approximate chemical composition of opal, SiO₂·nH₂O.
• The “n” in that chemical formula means that the amount of water mixed in with the silica dioxide is not really known.

Layers of pure fossilized diatom remains are called diatomite.

What’s Diatomaceous Earth?

Deposition of ocean or lake sediments in a messy business and it’s rare to find pure diatomite. Stuff like clay, silt and sand are usually mixed in with the fossilized diatoms. When you get a layer of mostly fossilized diatoms with just a little bit of clay and silt, it makes a white granular powder called diatomaceous earth and it’s really useful stuff.

• It used to be called fuller’s earth and was used to make felted wool cloth.
• Combined with the unstable explosive nitroglycerin, it forms dynamite. This is the invention that made Nobel all his money, which he then left to endow the founding of the Nobel Prizes.
• Because it is really effective at absorbing liquids, it’s used as an insecticide which dehydrates insects to death.
• It’s sometimes used as a clumping agent in kitty litter.
• It makes premium swimming pool filters.
• It can be used as insulation.
• Some diatomaceous earth is used as a food additive, mostly in cattle and chicken feed.

There are large diatomaceous earth quarries in Germany and the United States. There’s one right off of the Coal Canyon exit on I-80 outside of Lovelock, Nevada, on the way to several of my favorite mineral collecting sites. The stuff mined there is food-grade. It’s quite cheap to mine, which makes it very profitable.

Photo Credit

Picture of living diatoms by Wipeter, 2009, used under CC BY-SA 3.0 via Wikicommons

This work by Dr C M Helm-Clark PhD is licensed under a Creative Commons Attribution 4.0 International