oxides
Magnetite
Fe2+Fe3+2O4
- Also known as
- lodestonemagnetic iron ore
- Crystal system
- cubic
- Hardness
- 5.5–6.5 on the Mohs scale
- Lustre
- metallic
- Colour
- Black
- Where it forms
- In igneous and metamorphic rocks as an accessory mineral, and in banded iron formations. Naturally magnetised pieces are called lodestone.
- Chiefly from
- SwedenUral Mountains, RussiaNew York, United StatesMagnesia, Greece
Why it is that colour
Iron oxide with iron in two oxidation states, which is also the reason for its magnetism.
Safety
Safe to handle.
Where it comes from
A major iron ore, mined at scale in Sweden, Russia and Australia.
Historical use
The compass. Lodestone is naturally magnetised magnetite, and rubbing an iron needle on it transfers the magnetism — which is the technology behind every compass made before the nineteenth century and therefore behind a great deal of navigation and exploration.
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
Genuinely ancient and genuinely remarkable, because lodestone visibly does something. Greek sources from Thales onward discuss it, Chinese sources describe compass use by the eleventh century, and Pliny gives an origin story involving a shepherd named Magnes whose nails stuck to the ground. Medieval European lapidaries treat it extensively.
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.
Worth knowing
Lodestone is the strongest case in this entire collection for taking old beliefs about stones seriously as observation rather than fantasy. Here is a rock that moves iron without touching it, that transfers the power to a needle, and that points the needle consistently in one direction anywhere on earth. Any pre-modern account of that is going to sound occult, because there was no framework in which it was not.
And it was correct. Magnetism is real, action at a distance is real, and the compass built on it reorganised the world. When a medieval lapidary says a stone has a virtue, this is the one it is thinking of.
Magnetite also turns up in living things — in magnetotactic bacteria, in the beaks of pigeons, in salmon — where it appears to be involved in orientation. The animal magnetoreception literature is genuinely unsettled, and it is one of the few places where a stone in a body might be doing something.
Identity checked against IMA-CNMNC master list, June 2025.