No other pure element creates a stronger magnetic field. Holmium is the quiet record-holder of the periodic table. Cool it down, and it becomes the most powerful natural magnet known. Its laser saves hundreds of thousands of people from kidney stones every year.
This silvery lanthanide was named after Stockholm. In nature, it hides among other rare earth elements. There is only 1.3 grams per ton of Earth's crust. But without holmium, modern medicine and physics would lose a remarkable tool.
Holmium found its true calling in medicine. The Ho:YAG laser operates at 2.1 micrometers — a wavelength perfectly absorbed by water in body tissues. Surgeons use it to shatter kidney stones, remove tumors, and treat prostate conditions without large incisions. Over 500,000 such procedures happen worldwide each year. In nuclear energy, holmium absorbs neutrons and helps control chain reactions inside reactors.
Metallic holmium is stable in air and not toxic. But fine powder can self-ignite at 200 degrees C or from a spark — keep it away from fire. Ho2O3 dust irritates eyes and lungs. The LD50 of holmium chloride is about 5 g/kg, meaning toxicity is low. Work requires gloves, goggles, and a fume hood. Overall, holmium is one of the safest lanthanides.
Holmium is the strongest natural magnet among pure elements. Below 20 K, its magnetization reaches 3.8 T. That is twice as powerful as neodymium magnets.
The holmium laser saves over 500,000 patients each year. It shatters kidney stones into tiny fragments in just minutes — without a single incision.
Named after Stockholm — Holmia in Latin. Swedish chemist Per Teodor Cleve discovered it in 1878. It is one of the few elements named after a capital city.
Holmium has over 200 narrow absorption lines in the visible spectrum — more than any other element. That is why it is used to calibrate spectrophotometers.
Holmium gives synthetic diamonds (cubic zirconia) their beautiful yellow color. Just a tiny trace of Ho3+ ions is enough.
In nuclear reactors, holmium serves as a neutron absorber. It has one of the highest thermal neutron capture cross-sections at 64 barns.
| Isotope | Mass (u) | Abundance | Half-life | Decay |
|---|---|---|---|---|
165Ho | 164.930322 | 100.00% | stable | — |
Spectroscopic analysis of erbia