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Magnesium aluminum silicate

Magnesium aluminum silicate suppliers and sourcing guide

Magnesium aluminum silicate is a purified smectite clay, a blend of montmorillonite and saponite, mined and then refined to remove grit and other minerals. The clay is slurried in water, separated, dried and milled into flakes or powder. In water it hydrates into a colloidal dispersion that thickens on standing and thins when shaken, which keeps pigments and particles suspended. Brands buy NF or cosmetic grades, often to use alongside xanthan gum or cellulose gum.

See suppliersWhat to ask for on the COA
Also known as
Aluminum magnesium silicate · Aluminium magnesium silicate · Purified smectite clay · CAS 12511-31-8
Facts checked
November 2026

Forms and grades of magnesium aluminum silicate

Suppliers sell different products under the same name. Specify the one you need.

  • Flake and powder

    Flakes hydrate more slowly but dust less; powder hydrates faster. Both need high-shear mixing in water before other ingredients go in.

  • NF / pharmaceutical grade

    Material tested to the compendial monograph, which defines types by viscosity and by the ratio of aluminum to magnesium.

  • Cosmetic grades

    Grades chosen for viscosity, acid demand or electrolyte tolerance; the grade name sets how it behaves at low pH or with salts.

  • Blends with gums

    Pre-blends of the clay with xanthan gum or cellulose gum for easier processing; each component is declared separately on the label.

What to check on the COA

Compare each result with your own specification when the lot arrives.

Identity
X-ray diffraction or compendial identity tests for the smectite clay.
Viscosity
Brookfield viscosity of a 5% dispersion after a stated hydration time, against the range for the grade.
pH
pH of a 5% dispersion.
Loss on drying
Moisture content against the grade limit.
Heavy metals
Lead, arsenic, cadmium and mercury by ICP-MS after full acid digestion. Mined clays carry these from the deposit, so this is the test to read most closely on every lot.
Microbiology
Total aerobic count, yeast and mold, and absence of specified organisms such as E. coli, Salmonella, S. aureus and P. aeruginosa. Mined minerals pick up soil organisms, and some suppliers heat treat or otherwise reduce the count; the COA should say which.

Storage, lots and expiry

Storage and shelf life

Store the clay sealed in its bag in a dry place; it is stable as a dry mineral but absorbs moisture once opened. Hydrated dispersions are prone to microbial growth and should be preserved or used promptly. Shelf life follows the supplier's specification, with a retest of viscosity and microbiology for older stock.

Lots and expiry dates

Viscosity and metals results vary with the ore body, so record both for each lot and keep the supplier's grade name and lot on file. If suspension stability of a finished product is tight, check a test batch on a new lot before full production.

Regulatory status

Facts from regulators and standards bodies, each linked to its source.

  • Health Canada's Natural Health Products Ingredients Database lists aluminium magnesium silicate, also called magnesium aluminum silicate (CAS 12511-31-8), with non-medicinal purposes including emulsion stabilizer, opacifying agent, slip modifier and thickening agent.

    Source: webprod.hc-sc.gc.ca (opens in a new tab)

  • The same database has a separate entry for the hydrate (CAS 71205-22-6), with the non-medicinal purposes dispersing agent, stabilizing agent and thickening agent.

    Source: webprod.hc-sc.gc.ca (opens in a new tab)

This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.

Magnesium aluminum silicate suppliers

Manufacturers and distributors whose own websites say they sell it.

We are checking magnesium aluminum silicate suppliers now

Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.

Sell magnesium aluminum silicate? Request a listing

Frequently asked questions

What forms of magnesium aluminum silicate can brands buy?

Common forms include flake and powder, nF / pharmaceutical grade, cosmetic grades and blends with gums. Ask each supplier for the specification sheet of the exact grade they quote.

What should the COA for magnesium aluminum silicate include?

Expect identity, viscosity, pH, loss on drying, heavy metals and microbiology, each with its method, specification and result for that lot.

How should magnesium aluminum silicate be stored?

Store the clay sealed in its bag in a dry place; it is stable as a dry mineral but absorbs moisture once opened. Hydrated dispersions are prone to microbial growth and should be preserved or used promptly. Shelf life follows the supplier's specification, with a retest of viscosity and microbiology for older stock.

What is the regulatory status of magnesium aluminum silicate?

Health Canada's Natural Health Products Ingredients Database lists aluminium magnesium silicate, also called magnesium aluminum silicate (CAS 12511-31-8), with non-medicinal purposes including emulsion stabilizer, opacifying agent, slip modifier and thickening agent. The same database has a separate entry for the hydrate (CAS 71205-22-6), with the non-medicinal purposes dispersing agent, stabilizing agent and thickening agent.

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