What is a diatom?
A diatom (Greek - cut in two) is a mobile plant of microscopic single cell or colonial algae. Among the relatively simple forms of microscopic life are animals that cannot move and plants that can. One class of these mobile plants is known by the name of diatoms. A favorite subject in many general biology or botany classes, diatoms are also of interest to geology students because diatoms have been inhabitants of both fresh and salt water for at least 15,000,000 years, and possibly over 20,000,000.
As living plants, they serve as food stuff for animals as small as themselves and for the largest whales. As fossils, their siliceous skeletons form the substance of diatomaceous earth—once less accurately called kieselguhr—now generally mined, refined, and sold as diatomite. Diatoms reproduce by self-division, as suggested by the name. Under ideal conditions, each diatom may divide every eight hours. In thirty days a single diatom may produce ten billion descendants.
In the course of growth, a diatom extracts silica—the basic ingredient of common sand—from the water and converts it into a sort of external skeleton or frustule. When a diatom dies, it settles to the bottom of the sea or lake and the organic part disintegrates, leaving this siliceous skeleton, microscopic in itself and as full of tiny holes and passages as a sponge.
A cubic inch of diatomite contains millions of diatom fistulas, which is one way of dramatizing the fact that phenomenal growth over a period of ages was required to produce the vast deposits of diatomaceous earth. Some layers measure as much as 1,500 feet thick and extend over thousands of acres. The individual diatom comes in a great variety of shapes—well over 10,000 have been separately identified. Microscopic to sub-microscopic in size, their forms are as fanciful and delicate as snowflakes. The highest power microscopes reveal each minute particle as a mesh-like structure, a lacework spun for silica, the stuff of sand. The combination of minute size and frozen-lace particle structure accounts for the unusual and important properties of diatomite.
- Light Weight Compared to Buck (7 -13 lbs. per Cubic Foot)
- Large Surface Area per Pound (3,000 to 30,000 Square Feet)
- Absorptive Facility (Up to 300% by Weight)
- Liquid Suspendibility (Carried Easily by Very Light or Very Viscous Fluids)
Thanks to a certain proportion of elongated particles, a layer of diatomite tends to mat, like straw or felt. It is curiously both flexible and rigid in practical use, and a thick cake is almost incompressible although minute voids from 75 to 96% of its bulk. Diatomite is practically inert, being essentially the same chemically as common sand. The melting point is 2,900°F. It is friable and from grit.