Diatomite
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Diatomite
Environmental ChemistryBackground
Fig. 1. A Diatom. (Source: University of California Berkeley)
A diatom is an organism that is a member of the phylum of algae called Bacillariophyta. There are about 60,000 species of these algae presently known. Experts estimate that there are more likely 600,000 to 6,000,000 species in total!
Diatoms are single-celled (unicellular) organisms that live as individuals or in groups called colonies. They exist in all the waters of the Earth, both salt and fresh. They form shells made out of silica (the mineral name of this silica is opal) which they extract from the water. Their microscopic shells are very intricate and beautiful and have rightly been called "the jewels of the sea." Diatoms are very abundant and provide food for many aquatic animals.
When diatoms die, their silica shells accumulate on the floor of the body of water in which they lived. Thick layers of these diatom shells have been fossilized (that is, preserved) in the rock record. Such layers, or beds, of diatoms are called diatomaceous earth, or diatomite. Diatomaceous earth is white to cream color. It is very porous which makes it useful in a number of filtering applications.
Name
The name diatom comes from a Greek word diatomos that means cut in half, because the shells of diatoms have two overlapping, symmetrical halves.
Sources
In the United States, large deposits of diatomite are found in California, Nevada, Washington and Oregon. Of these states, California and Nevada produce the largest amount of diatomite. Significant producers of diatomite worldwide include France, China, Denmark, Russia, and Algeria. Diatomite resources worldwide will meet demand for the foreseeable future. However, new deposits that can be economically mined need to be identified.
The United States produces much of its own diatomite material. Still, some is imported from France, Mexico, and other nations.
Uses
Fig. 2. Another species of diatom. (Source: Mount Allison University)
Because of its porosity, diatomite has been used extensively as a filter for a variety of purposes. It is used to filter impurities out of everything from beer and wine to oils and greases. Similarly, diatomite is used to filter impurities from water to produce drinkable (potable) water in public water systems. In this situation, the diatomite removes bacteria and protozoa.
The oldest use of diatomite is as a very mild abrasive and for this purpose has been used in toothpaste and metal polishes.
It is also used in paper, paint, brick, tile, ceramics, plastics, soaps, detergents and other products as a filler. A filler is a substance that increases the volume of a product and/or fills in space.
Diatomite has also found value as an insulating material in high-temperature mechanisms like furnaces and boilers. It has also proven effective as a sound insulator.
Substitutes and Alternative Sources
Diatomite is easily replaced by other materials for most of its applications. For example, silica sand and an expanded form of the material perlite can be used in filtration applications. Talc, ground lime, ground mica, and clay can be used as filler material. Despite these many options, its ready availability, abundance and low cost will guarantee its use for many decades to come.
Further Reading
- Common Minerals and Their Uses, Mineral Information Institute.
- More than 170 Mineral Photographs, Mineral Information Institute.
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Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Mineral Information Institute. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Mineral Information Institute should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content. |
Citation
Mineral Information Institute (Lead Author);Sidney Draggan (Topic Editor) "Diatomite". In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth January 22, 2008; Last revised Date January 22, 2008; Retrieved February 10, 2012 <http://www.eoearth.org/article/Diatomite>
The Author
The Mineral Information Institute (MII) is a national 501 (c)(3) not-for-profit organization dedicated to educating youth about the science of minerals and other natural resources, and about their importance in our every day lives.
Each year MII works with interested professional and scientific associations, and various government and education agencies, to help classroom teachers develop materials that are directly usable by teachers in a variety of subjects and a multitude of grade levels. Al ... (Full Bio)
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