What Is Magnesium/Aluminum/Hydroxide/Carbonate?
Magnesium/Aluminum/Hydroxide/Carbonate is a blended mineral complex made from magnesium, aluminum, hydroxide and carbonate ions that bond together to form a fine white powder. It is sometimes described by the lengthy chemical name Carbonato(2-)hexadecahydroxybis(aluminium)hexamagnesium, but in cosmetics you will usually see the shorter INCI name on ingredient lists.
The raw minerals used to create this ingredient are typically sourced from mined deposits of magnesium and aluminum salts. After extraction, the minerals are refined and carefully reacted with purified water and carbon dioxide, triggering a controlled precipitation process that produces uniform particles with a specific surface area. The resulting powder is washed, dried and milled to achieve the right texture for cosmetic use.
Although magnesium and aluminum compounds have been part of topical preparations for many decades, the combined Magnesium/Aluminum/Hydroxide/Carbonate form gained popularity with formulators in the 1990s when the demand for smoother gel and cream textures grew. Its stability, mildness and ability to fine-tune thickness made it a reliable alternative to clays that can feel heavy or greasy.
Today you will find this ingredient in a variety of products, including clay-style masks, daily moisturizers, lightweight lotions, primer creams, anti-aging serums and even some sunscreen bases where a silky, non-runny feel is desired.
Magnesium/Aluminum/Hydroxide/Carbonate’s Cosmetic Benefits/Uses
The primary benefit of Magnesium/Aluminum/Hydroxide/Carbonate in skincare and makeup is its ability to control viscosity, or how thick and spreadable a formula feels. By dispersing evenly through water or oil phases, it helps create a cream or gel that is neither too runny nor too stiff. This makes application smoother and allows active ingredients to stay suspended for consistent performance across the entire product.
Who Can Use Magnesium/Aluminum/Hydroxide/Carbonate
This mineral thickener is generally considered suitable for all skin types, including oily, combination, normal and sensitive skin, because it is inert and has a low chance of causing irritation. Very dry skin might feel a slight sense of tightness if the final formula is low in emollients, so pairing it with a richer cream can help.
Because it is mined from mineral deposits and processed without animal derivatives, Magnesium/Aluminum/Hydroxide/Carbonate is appropriate for vegans and vegetarians.
Current research shows no specific risks for pregnant or breastfeeding women when the ingredient is used topically at cosmetic levels, but this is not medical advice. Anyone who is pregnant or nursing should share the full ingredient list of any new skincare product with a healthcare professional before use, just to be safe.
The ingredient does not increase photosensitivity, so it will not make skin more prone to sunburn. Standard daily sun protection is still recommended for overall skin health.
Potential Side Effects/Adverse Reactions
Responses to topical Magnesium/Aluminum/Hydroxide/Carbonate can differ from one person to another. The points below outline potential side effects, yet most users will not experience them if the product has been correctly formulated.
- Mild dryness or a transient feeling of tightness, especially on very dry skin
- Temporary redness or stinging on highly sensitive or compromised skin
- Rare allergic contact dermatitis in individuals with specific mineral sensitivities
- Possible clogging if used in an overly heavy formula on acne prone skin
- Texture changes or pilling when layered immediately with highly acidic products, which can lead to uneven application and minor irritation
If any of these issues occur discontinue use and seek medical advice if discomfort persists.
Comedogenic Rating
Rating: 1 / 5
Magnesium/Aluminum/Hydroxide/Carbonate is an inert mineral powder that has no inherent oil content and sits on the surface of the skin rather than absorbing into pores. Its particle shape is plate-like rather than waxy or greasy, so it does not readily trap sebum. For these reasons it carries a very low risk of clogging and earns a 1. Extremely occlusive or poorly formulated products that contain this ingredient alongside heavy oils could still cause congestion, but the mineral itself is not the culprit.
Suitable for acne-prone or breakout-prone skin in most formulations.
Because it can slightly mattify, some formulators use it in oil-control primers, which may be an added benefit for those dealing with excess shine.
Summary
Magnesium/Aluminum/Hydroxide/Carbonate is mainly a viscosity controller that fine-tunes the thickness of creams, gels and lotions so they spread smoothly and keep active ingredients suspended. By dispersing evenly through water and oil phases it gives formulas a silky, non-runny feel without adding greasiness.
While not a headline ingredient, it has carved out a steady following among formulators looking for a mild mineral thickener that improves texture without heaviness. You will spot it in masks, moisturizers, primers and some sunscreens where a light, velvety finish is desired.
Topically it is considered very safe for all skin types with a negligible comedogenic rating and a low likelihood of irritation. As with any new product, perform a quick patch test first to make sure your skin agrees with the complete formula.