What is Diatomaceous Earth?
Define Diatomaceous Earth - Diatomaceous Earth (DE) is a naturally occurring, soft and sedimentary rock that can be crumbled into a fine white to off white powder. It is also known as the diatomite or Kieselgur/kieselguhr, with the particle size ranging from less than three micrometres to more than one millimetre, but typically it is from 10 to 200 μm. The powder of the diatomaceous earth can have the abrasive feel the same as the pumice powder depending on the granularity and it has a low density as a result of its high porosity. The diatomaceous earth that is dried in the oven, is 80–90% silica, with 2–4% alumina, and 0.5–2% iron oxide.
Diatomaceous Earth Meaning - It is a fine siliceous earth composed chiefly of the cell walls of diatoms.
[Image will be Uploaded Soon]
Diatomaceous Earths contains the remaining fossilized diatoms, it is a type of hard-shelled protist. Diatomaceous earth can be used in the filtration aid, mild abrasive products including metal polishes and the toothpaste, mechanical insecticide, matting agent for coatings, absorbent for liquids, thermal insulators, activator in blood clotting studies, cat litter, porous support for the chemical catalysts, anti-block in the plastic films, reinforcing filler in plastics and rubbers, and soil for potted plants and trees like bonsai.
Composition
The composition of the diatomaceous earth is different for the different deposits, varying with the blend of the pure diatomaceous earth combined with other natural clays and minerals. The diatoms in each deposit vary in the quantity of the silica, depending on the age of the silica, the species of the diatom can also vary among the deposits. The species of the diatom mainly depends on the age and paleoenvironment of the deposit, in turn, the shape of the diatom is determined by the species.
Many deposits in British Columbia, such as Red Lake Earth are derived from the Miocene epoch, which contains Melosira granulata, a diatom species. These diatoms have a small globular form and are around 12 to 13 million years old. A deposit containing diatoms from this epoch will provide significantly more benefits than a deposit from a previous epoch. For example, diatoms from the Eocene epoch which is approximately 40 to 50 million years old are not more effective in their ability to absorb fluid, because as the diatoms get older it recrystallizes and their smaller pores will be filled with silica.
Formation
The formation of the diatomite occurs by the accumulation of the amorphous silica (opal, SiO₂ . nH₂O), which the remaining dead diatoms in lacustrine or marine sediments. A pair of symmetrical shells, or frustules, make up the fossil remains. Marine diatomites can be found in a number of other rock types, but lacustrine diatomites are almost exclusively found with volcanic rock. The diatomite in diatomaceous chert has been cemented with silica.
Diatoms can remove amorphous silica from water with less than 1% amorphous silica saturation. Since they are surrounded by an organic matrix, their frustules do not dissolve. Clay minerals may also form on the frustules, preventing them from dissolving in the seawater. The frustule is stripped of its organic coating and exposed to seawater when the diatom dies. As a result, only 1% to 10% of frustules live long enough to be buried under sediments, and some of this is dissolved. In the sedimentary record, only about 0.05 percent to 0.15 percent of the original amount of silica generated by diatoms is stored.
Discovery
Diatomaceous earth was discovered by German peasant Peter Kasten In 1836 or 1837, when saw sinking a well on the northern slopes of the Haußelberg hill, in the Lüneburg Heath in North Germany.
Extraction and storage sites in the Lüneburg Heath
Neuohe – extraction from 1863 to 1994
Wiechel from 1871 to 1978
Hützel from 1876 to 1969
Hösseringen from c.1880 to 1894
Hammersdorf from c.1880 to 1920
Oberohe from 1884 to 1970
Schmarbeck from 1896 to c. 1925
Steinbeck from 1897 to 1928
Breloh from 1907 to 1975
Schwindebeck from 1913 to 1973
Hetendorf from 1970 to 1994
Commercial Forms
Diatomaceous earth is found commercially in many forms:
Diatomaceous earth granulated is a raw material that has been crushed for easy packaging.
Diatomaceous earth that has been milled or micronized is particularly fine (10 μm to 50 μm) and is used in insecticides.
For filters, calcined diatomaceous earth is heat-treated and activated.
Usage
There are several uses of the diatomaceous earth, some of them are explained below:
Explosives - Alfred Nobel in 1866 discovered that absorbing nitroglycerin in diatomite made it much more stable. This makes transporting and treating nitroglycerin in its raw form much safer. In 1867, he patented this mixture as dynamite, and it is also known as guhr dynamite.
Filtration - Wilhelm Berkefeld, a Celle engineer, recognised diatomaceous earth's filtering ability and created tubular filters (also known as filter candles) driven by diatomaceous earth. These Berkefeld filters were successfully used during the cholera outbreak in Hamburg in 1892. Diatomaceous earth, in one form, is used as a filter medium, especially in swimming pools.
Abrasive - Diatomite's oldest application is as a very mild abrasive, and it's been used in toothpaste, metal polishes, and even some facial scrubs for this reason.
Pest Control - Diatomite's abrasive and physico-sorptive properties make it useful as an insecticide. The fine powder absorbs lipids from the waxy outer layer of several insect exoskeletons, which serves as a shield to prevent water vapour from escaping the insect's body. The evaporation of water from their bodies is increased when the layer is damaged, causing them to become dehydrated, often fatally.
Thermal - Its thermal properties allow it to be used as a fire-resistant safe's barrier material. It's also used in cryogenic-safe evacuated powder insulation. To improve the efficacy of vacuum insulation, diatomaceous earth powder is injected into the vacuum room. It was used as a thermal heat barrier in traditional AGA cookers.
Catalyst Support - Diatomaceous earth is often used as catalyst support, primarily to increase the surface area and operation of the catalyst. To boost its operation as a hydrogenation catalyst, nickel can be assisted on the material (the combination is known as Ni–Kieselguhr).
Agriculture - Natural freshwater diatomaceous earth is used in agriculture as an anti-caking agent and insecticide for grain storage. The Food and Drug Administration has approved it as a feed additive to avoid caking.
Construction - The diatomaceous earth spent in the process of brewing can be added to the ceramics for the manufacturing of red bricks with higher open porosity. Diatomaceous earth is considered one of the most prominent inorganic, non-metallic materials. Which can be used for the production of different ceramics, along with the production of porous ceramics under low-temperature hydrothermal technology.
FAQs on Diatomaceous Earth
1. What is diatomaceous earth and how is it formed?
Diatomaceous earth is a naturally occurring, soft, siliceous sedimentary rock that crumbles easily into a fine white or off-white powder. It is formed from the fossilised remains of tiny, aquatic organisms called diatoms. Over millions of years, the skeletons of these diatoms, which are made of a substance called silica, accumulated in the sediments of rivers, lakes, and oceans. This massive accumulation resulted in the formation of diatomaceous earth deposits.
2. What is diatomaceous earth also known as?
Diatomaceous earth is also commonly known by other names, including diatomite, kieselgur, or kieselguhr. While these terms are often used interchangeably, they all refer to the same fossil-based siliceous powder.
3. What are the major uses of diatomaceous earth?
Due to its unique properties, diatomaceous earth has a wide range of applications. Some of its major uses include:
- Filtration: It is widely used to filter fine particles from liquids, such as in swimming pools, beer brewing, and winemaking.
- Pest Control: It acts as a natural insecticide to control pests like ants, fleas, bed bugs, and slugs.
- Abrasive: It is used as a mild abrasive in products like metal polishes and toothpaste.
- Absorbent: Its porous nature makes it an excellent absorbent for industrial spills and as cat litter.
- Gardening: It is used in gardening to improve soil structure and as a growing medium in hydroponics.
4. How does diatomaceous earth work as a natural insecticide?
Diatomaceous earth works mechanically, not chemically. The microscopic sharp edges of the diatom fossils scratch the waxy outer layer of an insect's exoskeleton. This abrasive action, combined with the powder's high absorbency, soaks up the oils and fats (lipids) from the exoskeleton, causing the insect to dehydrate and die. It is a physical process of desiccation.
5. How is diatomaceous earth covered in the CBSE Class 11 Biology syllabus?
In the CBSE Class 11 Biology syllabus for the session 2025-26, diatomaceous earth is discussed in Chapter 2: Biological Classification, under Kingdom Protista. The topic covers Chrysophytes, which include diatoms. The syllabus explains that diatoms have indestructible siliceous cell walls that accumulate over billions of years to form what is known as 'diatomaceous earth'. Its gritty nature and use in polishing and filtration are highlighted.
6. What is the difference between food-grade and filter-grade diatomaceous earth?
The main difference lies in the processing and silica content. Food-grade diatomaceous earth is uncalcined (not heat-treated) and comes from natural freshwater sources. It has very low levels of crystalline silica, making it safe for consumption. In contrast, filter-grade (or pool-grade) is calcined, meaning it's heat-treated to improve its filtering properties. This process significantly increases the concentration of crystalline silica, which is harmful if inhaled or ingested.
7. Why are the properties of diatomaceous earth, like being gritty and porous, so unique?
The unique properties of diatomaceous earth stem directly from the structure of the fossilised diatoms it's made from. Each microscopic diatom skeleton is incredibly intricate, full of tiny holes, and has sharp, siliceous edges. This microscopic porosity is why it is so lightweight and absorbent. The hardness and sharpness of the silica material give it its gritty, abrasive quality. It's essentially a powder made of countless tiny, hard, and hollow fossils.
8. Where is diatomaceous earth typically found and how is it extracted?
Diatomaceous earth is found in deposits around the world, which are remnants of ancient water bodies—both freshwater and saltwater. Major deposits exist in the United States, China, Denmark, and Peru. It is extracted through surface mining. The overlying earth (overburden) is removed, and the diatomite rock is then dug or scraped out from the deposit bed. After mining, it is crushed, dried, and milled into a fine powder for various applications.
9. Is it safe for humans and pets to consume food-grade diatomaceous earth?
When specifically labelled as food-grade, diatomaceous earth is generally considered safe for consumption in small amounts as it is amorphous (non-crystalline) silica. It is often marketed as a dietary supplement. However, it is crucial to only use the food-grade version and avoid inhaling the dust, as any fine powder can irritate the lungs. Filter-grade diatomaceous earth is toxic and must never be consumed.
10. Does diatomaceous earth have an Indian name?
Diatomaceous earth does not have a common, traditional name in Indian languages like Hindi. It is most often referred to by its English name, "diatomaceous earth," or its scientific name, "diatomite." In commercial contexts, it may sometimes be referred to simply as "silica powder," though this is a more general term.
