What is “Magnesium Aluminum Silicate” and what is its purpose?

Magnesium Aluminum Silicate is a mineral-derived ingredient belonging to the phyllosilicate family, specifically clays. Chemically, it is a hydrated silicate of magnesium and aluminum composed of stacked sheets arranged in lamellar structures. This layered architecture gives it unique physicochemical properties, including a high adsorption capacity and an ability to interact with water. When dispersed in an aqueous phase, Magnesium Aluminum Silicate forms a three-dimensional network capable of trapping water between its sheets, which explains its thickening and stabilizing behavior.

Did you know? Ancient civilizations, particularly in Egypt and Greece, were already using silicate-rich clays for their absorbent and protective properties.

In cosmetic formulations, magnesium aluminum silicate is noted for its chemical stability and its compatibility with a broad range of ingredients, whether hydrophilic or lipophilic. Insoluble in water, it nonetheless swells upon contact, forming stable colloidal dispersions. This property is particularly valuable for structuring emulsions, reducing phase separation and enhancing the longevity of formulations. It also demonstrates good resistance to pH fluctuations and heat. Inert, Magnesium Aluminum Silicate is mainly employed for its technical functions rather than any biological activity on the skin.

In cosmetics, Magnesium Aluminum Silicate is primarily used for its structuring functions within formulations. It contributes to adjusting the viscosity of skincare products, stabilizing emulsions, and maintaining a uniform distribution of various components, especially when the formula contains pigments, powders, or insoluble active ingredients. Thanks to its ability to form a colloidal network in water, it reduces sedimentation and phase separation phenomena, thereby improving product stability over time.

Beyond its purely formulatory interest, aluminum magnesium silicate is also valued for its immediate visual effect on the skin. When applied, it helps form a thin, continuous film on the surface of the epidermis. As it dries, this film exerts a slight mechanical tension on the stratum corneum, generating a instant lifting effect. This physical action temporarily smooths the skin, resulting in a visible reduction in the appearance of wrinkles and fine lines, particularly the expression lines.

Due to its immediate tightening effect, Magnesium Aluminum Silicate integrates especially well into formulas that also combine long-term acting active ingredients targeting skin aging, providing both progressive and instant action.

Magnesium Aluminum Silicate is a mineral-derived ingredient produced by a synthetic process designed to replicate a stable clay-like structure. One of the most common manufacturing methods relies on the reaction of soluble magnesium and aluminum salts with a silicate source. In practice, aqueous solutions of magnesium sulfate and aluminum sulfate are first prepared and then combined with a sodium silicate solution, often in the presence of sodium hydroxide. This step allows for the gradual formation of an aluminum and magnesium silicate network. The subsequent addition of calcium chloride promotes the precipitation of the final compound, which is then washed, purified, and dried to yield a fine, stable powder suitable for cosmetic use.

Other synthesis methods exist, notably processes involving a high-temperature crystallization phase. In this case, a solution containing soluble magnesium and aluminum salts is mixed with a silicate emulsion, sometimes enriched with agents that promote crystalline organization. The mixture is then held at temperatures ranging from 100 to 220 °C for several hours. This thermal step induces the formation of a well-ordered lamellar structure, giving Magnesium Aluminum Silicate its characteristic rheological properties, such as its ability to thicken and structure formulations.

Magnesium Aluminum Silicate is an ingredient with an excellent safety profile, presenting a minimal risk of skin irritation or sensitization.

According to the Cosmetic Ingredient Review Panel, an independent group of dermatology, toxicology and pharmacology experts, this ingredient shows no notable toxicity in animal studies. For example, tests on mice were conducted at doses up to 5 mg/kg with no toxic effects observed.

In terms of irritation and sensitization, a study indicates that Magnesium Aluminum Silicate may be slightly irritating to rabbit skin (tested concentration: 4%), but it does not cause any cumulative irritation in guinea pigs at the same dosage. Clinical trials in humans, involving the daily application of 2 g to a small skin area for one week, revealed no adverse effects. Regarding eye irritation, animal tests showed no notable effects. However, it is important to note that safety around the eye contour depends on the overall product formulation and cannot be guaranteed by the presence of magnesium aluminum silicate alone.

Furthermore, animal studies indicate that Magnesium Aluminum Silicate shows no adverse effects on systemic toxicity, reproduction, or fetal development, even at high doses. It is not teratogenic and does not negatively affect embryonic development. This ingredient is therefore fully compatible with pregnancy. In addition, genotoxicity tests conducted on bacteria and cell cultures have confirmed the absence of any genotoxic risk.

Finally, the primary risk concerns inhalation of concentrated dust, which can occur in occupational settings where particles are handled dry. In cosmetic formulations, aluminum and magnesium silicate particles are not respirable and are present at very low concentrations, making the risk negligible. However, a special attention is needed for spray products, to minimize any accidental inhalation.

• Cosmetic Ingredient Review Panel. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite. International Journal of Toxicology (2003).

• EVTUGUIN D. V. & al. Silica-based nanocoating doped by layered double hydroxides to enhance the paperboard barrier properties. World Journal of Nano Science and Engineering (2015).

• 강학희 & al. Development of immediate face lifting technology for reducing wrinkles by using film-forming agent. Journal of the Society of Cosmetic Scientists of Korea (2018).

• RENTSCH D. & al. Aluminum incorporation into magnesium silicate hydrate (M-S-H). Cement and Concrete Research (2020).

• BOZKURT H. K. & al. Developing various lotion formulas wrinkle remover. South Florida Journal of Development (2024)

• JAIPAKDEE N. & al. A simple reinforcement of native starch agglomerates using magnesium aluminum silicate: A study with tapioca starch and its application as a tablet diluent material. Journal of Drug Delivery Science and Technology (2025).