carbonates
Magnesite
Mg(CO3)
- Also known as
- magnesium carbonate
- Crystal system
- trigonal
- Hardness
- 3.5–4.5 on the Mohs scale
- Lustre
- vitreous
- Colour
- White, grey, occasionally yellowish
- Where it forms
- By alteration of magnesium-rich rocks such as serpentinite, and in sedimentary deposits.
- Chiefly from
- Liaoning, ChinaAustriaBrazilAustralia
Why it is that colour
White when pure. Like howlite, its commercial role depends on being white, porous and dyeable.
Safety
Safe to handle. Magnesium carbonate is the gymnasts’ chalk and is used as an antacid; the mineral itself is benign.
Where it comes from
Mined at large scale for refractory magnesia, used in steelmaking furnace linings. China dominates. The dyed beads sold as turquoise and lapis are an incidental trade on the edge of a bulk industrial mineral.
Historical use
Its industrial role is substantial and its ornamental role is negligible except as an imitation.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
No traditional attribution. Its presence in the crystal trade is largely as a dyed substitute.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Sold as this, but not
Worth knowing
Magnesite is the other great substitute, alongside howlite, and the two are used interchangeably for the same purpose. If a strand of turquoise beads is uniform in colour, evenly veined and suspiciously cheap, it is one of these two, dyed.
There is nothing wrong with the material. It is a real mineral with a real industrial life lining steel furnaces. The problem is only ever the label.
Identity checked against IMA-CNMNC master list, June 2025.