Diatomaceous Earth is a naturally occurring, fine-powdery sedimentary rock primarily composed of fossilized diatom shells rich in amorphous silica (SiO₂). In skincare formulations, it is valued for its absorbent and mild exfoliant properties: it helps remove excess oil, surface impurities and dead skin cells while offering texturising support in masks, powders and matte-finish products. Its high porosity and inertness also make it effective as a bulking or anticaking agent in pressed powders, foundations or cleansers that seek oil-control and refined feel.

In hair-care systems, although less widely discussed, Diatomaceous Earth can offer scalp-care benefits through its absorbent capacity to manage sebum, support scalp exfoliation and contribute to cleaner hair scalp surfaces. Its particulate nature also allows it to act as a texturising filler in dry shampoo or styling powders to improve mattification and volume control. However, its use in hair-care is more niche and typically focuses on physical rather than biochemical functionality.