What is Diatomaceous Earth? Formation, Mineral Structure and Diatom Remnant Principle

Diatomaceous earth (DE), also known as diatomite, is a unique natural biogenic siliceous mineral formed by the fossilization of ancient aquatic microorganisms. Unlike traditional mineral resources formed by geological magmatism or sedimentary rock weathering, diatomaceous earth is a biological sedimentary rock derived entirely from the remains of single-celled aquatic algae called diatoms. With excellent porous structure, stable chemical inertness, high specific surface area and unique microscopic morphological characteristics, diatomaceous earth has become a multi-functional green mineral material widely used in filtration, adsorption, industrial fillers, environmental protection, agriculture and daily chemical industries.

In industrial applications, the structural differences of diatom frustules determine product grades and application scenarios. Among all types of diatomite, linear diatomaceous earth with ordered straight-through pore structure represents the highest-grade raw ore resources. This article systematically explains the definition, geological formation process, biological remnant principle, microscopic mineral structure and structural classification characteristics of diatomaceous earth, helping to fully understand the essential characteristics of diatomite materials.

Diatomaceous earth is a natural soft sedimentary mineral composed of the fossilized cell walls of ancient diatoms. Its main chemical component is amorphous hydrated silica (SiO₂·nH₂O), accompanied by a small amount of alumina, iron oxide, calcium oxide and other trace mineral components. Pure diatomaceous earth is white or off-white, with low bulk density, strong porosity, good adsorption performance and excellent chemical stability.

As a typical biogenic mineral, diatomite is fundamentally different from inorganic minerals such as quartz sand, kaolin and talc powder. Its core characteristic is the reserved biological porous skeleton structure, which endows diatomaceous earth with irreplaceable functional advantages in filtration, adsorption and modification applications.

The formation of diatomaceous earth is a long-term geological evolution process spanning millions of years, including biological reproduction, sedimentary accumulation, diagenesis and fossilization.

Stage 1: Mass reproduction of diatoms. In ancient lakes, shallow seas and freshwater basins with suitable temperature, sufficient light and rich nutrients, a large number of single-celled diatoms reproduced rapidly. Diatoms are siliceous algae that can absorb dissolved silicon in water to synthesize hard silica cell walls, which support and protect their biological cells.

Stage 2: Sedimentary accumulation of diatom remains. After the death of diatoms, the organic cellular tissues gradually decomposed and disappeared, while the durable silica cell walls sank to the bottom of water bodies and accumulated in layers. After long-term continuous accumulation, a thick layer of diatom frustule sediment was formed at the bottom of ancient water basins.

Stage 3: Geological diagenesis and fossilization. With the changes of crustal movement, water body recession and geological sedimentation, the diatom sediment layer was covered by mud and sand layers. After long-term compression, dehydration and geological fossilization under natural environments, the loose diatom sediment finally formed stable solid diatomaceous earth ore layers.

Due to different ancient water environments and geological conditions, diatomite ores formed in different regions show different microscopic morphologies, among which ordered linear diatom frustules and disordered circular or oval frustules are the two mainstream structural types.

The unique performance of diatomaceous earth originates from the biological structure of diatom remnants. Different from ordinary rock minerals, diatomite retains the complete microscopic skeleton of ancient diatom organisms.

The cell wall of diatoms is composed of high-purity amorphous silica with stable three-dimensional pore structure. This biological silicon structure has strong weathering resistance and corrosion resistance, which can remain intact after millions of years of geological changes. After the organic components of diatoms are completely decomposed, the pure siliceous porous skeleton is retained, forming the unique porous microscopic morphology of diatomaceous earth.

The core difference between high-grade linear diatomaceous earth and ordinary diatomite lies in the biological growth structure of diatom remnants. High-quality linear diatoms grow with regular straight-through linear pore channels, neat arrangement and uniform pore size; while ordinary diatom frustules are mostly circular, disordered and irregular in pore distribution. This essential biological difference directly determines the filtration accuracy, adsorption efficiency and industrial application grade of diatomaceous earth products.

Diatomaceous earth has a unique porous biological skeleton structure. High-purity diatomite has a porosity of more than 80%, with a large number of micron and sub-micron pore channels on the surface and inside the frustules. Linear diatomaceous earth has ordered straight-through linear pores, with smooth pore walls and uniform pore diameter, forming a stable open pore system. Ordinary diatomite presents disordered, staggered and closed pore structures with low effective pore utilization rate.

High chemical stability. The main component is inert amorphous silica, which is insoluble in water, acid and weak alkali solutions, and does not react with most chemical substances, without secondary pollution risk.

Strong adsorption capacity. The huge specific surface area formed by the porous structure enables diatomite to efficiently adsorb organic molecules, suspended particles, odor substances and trace impurities.

Lightweight and low density. The hollow porous structure makes diatomaceous earth have low bulk density, good suspension and excellent filling and dispersing performance.

High temperature resistance. Siliceous biological skeleton has good thermal stability, non-combustible and low thermal conductivity, with excellent thermal insulation and fire resistance.

According to the microscopic morphology of diatom remnants, diatomaceous earth is mainly divided into ordinary disordered diatomite and high-grade linear diatomaceous earth.

Ordinary diatomaceous earth: The frustules are mostly circular and irregular, with disorderly distributed pores, many dead holes and closed holes, low effective pore utilization rate, unstable filtration and adsorption effects, and are mostly used in low-end filling and coarse filtration fields.

Linear diatomaceous earth: It is a high-quality rare diatomite resource with regular ordered linear straight-through pore channels, uniform pore size, no dead holes, high structural stability and high effective pore utilization rate. It has absolute advantages in high-precision filtration, high-efficiency adsorption, high-end catalyst carrier and functional modification, and is the core raw material for high-end industrial applications.

Diatomaceous earth is a precious natural biogenic siliceous mineral formed by the fossilization of ancient diatom remains through millions of years of geological evolution. Its unique porous structure, stable chemical properties and excellent physical characteristics originate from the biological skeleton of diatom remnants. The ordered linear pore structure of high-grade linear diatomaceous earth further endows it with higher industrial value, making it an irreplaceable high-performance green functional material in modern industry, environmental protection, agriculture and daily chemical fields. Understanding the formation principle and structural characteristics of diatomaceous earth is the basis for rational development and high-value utilization of diatomite resources.