What is "Magnesium Aluminium 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 magnesium and aluminium silicate composed of superimposed sheets organised into layered structures. This layered architecture gives it distinctive physicochemical properties, notably 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 behaviour.

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

In cosmetic formulation, magnesium aluminium silicate stands out for its chemical stability and its compatibility with a wide range of ingredients, whether hydrophilic or lipophilic. Insoluble in water, it nevertheless swells upon contact, forming stable colloidal dispersions. This feature is particularly valuable for structuring emulsions, reducing phase separation and improving the long-term stability of formulations. It also exhibits good resistance to pH variations and heat. Inert, magnesium aluminium silicate is employed more for its technical properties than for any biological activity on the skin.

In cosmetics, Magnesium Aluminum Silicate is primarily employed for its structuring functions within formulations. It helps to adjust the viscosity of skincare products, stabilise emulsions and maintain a homogeneous distribution of various components, particularly when the formulation contains pigments, powders or insoluble actives. Thanks to its ability to form a colloidal network in water, it minimises sedimentation and phase separation, thereby enhancing the product’s stability over time.

Beyond its purely formulating role, aluminium magnesium silicate is also sought after for its immediate visual effect on the skin. Upon application, it contributes to the formation of 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 an instant tightening effect. This physical action temporarily smooths the skin, leading to a visible reduction in the appearance of wrinkles and fine lines, notably the expression lines.

Thanks to its immediate tightening effect, Magnesium Aluminium Silicate integrates particularly well into formulations that also combine active ingredients acting in the long term on the skin ageing, thereby providing both gradual and instantaneous effects.

Magnesium Aluminum Silicate is a mineral-derived ingredient produced via 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 aluminium salts with a silicate source. Specifically, aqueous solutions of magnesium sulphate and aluminium sulphate are first prepared, then mixed with a sodium silicate solution, often in the presence of sodium hydroxide. This step facilitates the gradual assembly of an aluminium-magnesium silicate network. The subsequent addition of calcium chloride induces the precipitation of the final compound, which is then washed, purified and dried to produce a fine, stable powder suitable for cosmetic use.

Other synthesis methods exist, notably processes involving a high-temperature crystallisation phase. In this case, a solution containing soluble magnesium and aluminium salts is mixed with a silicate emulsion, sometimes enriched with agents that facilitate crystal organisation. The mixture is then held at temperatures between 100 and 220 °C for several hours. This thermal stage 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 Aluminium Silicate is an ingredient that exhibits an excellent safety profile, with minimal risk of skin irritation or sensitisation.

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

In terms of irritation and sensitisation, a study indicates that Magnesium Aluminium Silicate may be slightly irritating to rabbit skin (tested at 4%), but it causes no cumulative irritation in the guinea pig at the same dosage. Human clinical trials, involving daily application of 2 g to a small area of skin for one week, did not reveal any adverse effects. Regarding ocular 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 solely by the presence of aluminium and magnesium silicate.

Moreover, animal studies indicate that magnesium aluminium silicate exhibits no adverse effects on systemic toxicity, reproduction or foetal development, even at high doses. It is not teratogenic and does not induce any negative effects on 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 main hazard concerns the inhalation of concentrated dust, which can occur in occupational settings where particles are handled in a dry state. In cosmetic formulations, aluminium and magnesium silicate particles are not respirable and occur at very low concentrations, rendering the risk negligible. However, a particular care is necessary for spray products, in order to minimise 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).