Today, we know that iron is the most abundant metal in Earth’s crust, and we use it in many of our building projects. But thousands of years ago, people knew iron best as the metal that fell from the sky in meteorites.

Iron is the last of the ancient alchemists’ seven metals. Traditionally associated with the planet Mars and ideas of protection, iron’s use in tools and weapons changed the ancient world. That said, iron isn’t a “perfect” metal — it does oxidize (rust), and these days we strengthen it with carbon to make steel. But rust itself was thought of as a tonic, particularly by the Greeks.

In fact, iron was used as a medicine through the 18th century. Special “secret preparations” of the metal, known generally as “salts of Mars,” were used to treat diseases and promote strength. Today, we still recognize iron as an important vitamin (and component of our blood!) but we usually prefer to ingest it through fortified cereals (or dark chocolate!). 🙂

What about “cold iron,” or the idea that an iron horseshoe above your door can protect you from fairies, ghosts, and even dragons? Well, the folklore surrounding iron is murky (even in modern times: while researching, I found a lot of controversy over whether steel has the same effects!). One article I read suggested that this superstition has its roots in the fact that early Britons were the inspiration for ideas of “fairy folk.” Those Britons fought with bronze and eventually were defeated by invaders with iron weapons. While this does seem a logical explanation, it’s a sad twist on the idea of protective iron!

Selected Sources

“Iron: Fact Sheet for Health Professionals.” National Institutes of Health. Find it here.

Jackson, Tom. The Elements: An Illustrated History of the Periodic Table. Shelter Harbor Press: NY, 2020.

Thompson, CJS. Alchemy and Alchemists. Dover Publications, Inc: Mineola, NY, 2002.