Magnesium carbonate
Magnesium carbonate suppliers and sourcing guide
Food-grade magnesium carbonate is a basic magnesium carbonate, also called magnesium carbonate hydroxide, with a formula close to (MgCO3)4·Mg(OH)2·5H2O. It is a white powder formed by adding an alkaline carbonate to a magnesium sulfate solution or by carbonating a slurry of magnesium hydroxide and boiling the product. Light and heavy grades differ mainly in bulk density, and brands buy it as a magnesium source for tablets and capsules and as a flow and drying agent.
- Category
- Vitamins and minerals
- Also known as
- Magnesium carbonate hydroxide · Basic magnesium carbonate · E504 · Magnesium hydroxide carbonate
- Facts checked
- November 2026
Forms and grades of magnesium carbonate
Suppliers sell different products under the same name. Specify the one you need.
Light magnesium carbonate
Very bulky, low-density powder used as a flow agent and carrier.
Heavy magnesium carbonate
Denser powder preferred for tablets and capsules where volume is limited.
Directly compressible granules
Granulated grades for tablet presses.
Natural magnesite
Mined magnesium carbonate, sold in some markets; impurity profile depends on the ore.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Assay as magnesium oxide
- Magnesium content expressed as MgO after ignition, by EDTA titration, against a Food Chemicals Codex or USP specification.
- Calcium oxide and soluble salts
- Limits for calcium and water-soluble salts carried from the raw materials.
- Acid-insoluble substances
- Insoluble mineral matter, mostly from mined sources.
- Lead, arsenic and other metals
- Heavy metals by ICP-MS.
- Bulk density
- Tapped or poured density, which separates light from heavy grades and sets capsule fill.
Storage, lots and expiry
Storage and shelf life
Store magnesium carbonate in closed bags in a dry area, away from acids, which release carbon dioxide from it. The light grade picks up odors and moisture readily, so keep it sealed. Shelf life is set by the supplier's specification, with assay and moisture retested on aged lots.
Lots and expiry dates
Record the grade (light or heavy), bulk density and assay as MgO for each lot. Density differences between lots change capsule fill weight and flow behavior, so check them before production.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 184.1425 affirms magnesium carbonate as GRAS for uses that include anticaking and free-flow agent, nutrient supplement and pH control agent.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Permitted Anticaking Agents includes magnesium carbonate for uses including garlic salt and onion salt.
Source: canada.ca (opens in a new tab)Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists magnesium carbonate among the source ingredients for magnesium (Table 2).
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 carbonate suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking magnesium carbonate 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 carbonate? Request a listingFrequently asked questions
What forms of magnesium carbonate can brands buy?
Common forms include light magnesium carbonate, heavy magnesium carbonate, directly compressible granules and natural magnesite. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for magnesium carbonate include?
Expect assay as magnesium oxide, calcium oxide and soluble salts, acid-insoluble substances, lead, arsenic and other metals and bulk density, each with its method, specification and result for that lot.
How should magnesium carbonate be stored?
Store magnesium carbonate in closed bags in a dry area, away from acids, which release carbon dioxide from it. The light grade picks up odors and moisture readily, so keep it sealed. Shelf life is set by the supplier's specification, with assay and moisture retested on aged lots.
What is the regulatory status of magnesium carbonate?
21 CFR 184.1425 affirms magnesium carbonate as GRAS for uses that include anticaking and free-flow agent, nutrient supplement and pH control agent. Health Canada's List of Permitted Anticaking Agents includes magnesium carbonate for uses including garlic salt and onion salt. Health Canada's Multi-Vitamin/Mineral Supplements monograph for natural health products lists magnesium carbonate among the source ingredients for magnesium (Table 2).
More vitamins and minerals
- Magnesium GlycinateMagnesium bisglycinate · Magnesium bisglycinate chelate
- Vitamin CL-ascorbic acid · Ascorbic acid
- Vitamin D3Cholecalciferol · Colecalciferol
- ZincZinc citrate · Zinc gluconate
- Vitamin A palmitateRetinyl palmitate · Retinol palmitate
- Vitamin A acetateRetinyl acetate · Retinol acetate
- Beta-caroteneβ-Carotene · all-trans-beta-carotene
- Vitamin D2Ergocalciferol · Calciferol
- Vitamin E (d-alpha tocopherol)d-alpha-tocopherol · RRR-alpha-tocopherol
- Mixed tocopherolsTocopherols concentrate, mixed · Mixed tocopherol concentrate
- Vitamin K1Phylloquinone · Phytonadione
- Vitamin K2 (MK-7)Menaquinone-7 · MK-7
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