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Material World
Element · Ho

Holmium

The most magnetic of the elements, and the source of a laser wavelength that water absorbs almost completely.

Optical medium Medicinal

Holmium has the largest magnetic moment of any element, which makes it useful inside the pole pieces of very strong magnets — it concentrates flux in a way that iron cannot.

Its other use rests on a coincidence of wavelength. A holmium laser emits at a wavelength water absorbs almost completely, so its energy is deposited in a fraction of a millimetre of tissue instead of penetrating. That makes it a cutting tool rather than a heating one.

Uses

Holmium-doped lasers are used in surgery, particularly for breaking up kidney stones and for prostate procedures, because the shallow absorption depth gives control and limits damage to what is behind the target.

Holmium is also used to shape the field in high-strength magnets, and its sharp absorption bands make it a convenient wavelength reference for calibrating optical instruments.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

is produced by

  • Rare earth separation — process · a heavy rare earth; the separation is the same cascade, run longer because the differences are smaller

is found in

  • Yttrium aluminium garnet — compound · for the wavelength used to break kidney stones, and effectively the only reason holmium is produced

Sources

  • Material World
    Our own writing
  • Wikidata
    Wikimedia Foundation · Creative Commons CC0 1.0 Universal (public domain dedication)
  • PubChem
    US National Library of Medicine · Mixed — aggregated third-party content, rights retained by depositors

Questions this page answers

Where it comes from, and what it becomes

Follow Holmium back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

  • Holmium → is produced by (a heavy rare earth; the separation is the same cascade, run longer because the differences are smaller) → Rare earth separation → takes as input (the principal ore of the light rare earths, carrying all of them together) → Bastnäsite
  • Holmium → is produced by (a heavy rare earth; the separation is the same cascade, run longer because the differences are smaller) → Rare earth separation → takes as input (the other feed alongside bastnäsite, bringing thorium into the residues with it) → Monazite
  • Holmium → is produced by (a heavy rare earth; the separation is the same cascade, run longer because the differences are smaller) → Rare earth separation → takes as input (the heavy rare earth feed, where monazite and bastnäsite bring the light ones) → Xenotime