Holmium is a chemical element with symbol Ho and atomic number 67.
- Has the highest magnetic strength of any element, and therefore is used to create the strongest artificially generated magnetic fields, when placed within high-strength magnets as a magnetic pole piece (also called a magnetic flux concentrator). Since it can absorb nuclear fission-bred neutrons, it is also used as a burnable poison to regulate nuclear reactors.
- Used in yttrium-iron-garnet (YIG)- and yttrium-lanthanum-fluoride (YLF) solid-state lasers found in microwave equipment (which are in turn found in a variety of medical and dental settings). Holmium lasers emit at 2.1 micrometres. They are used in medical, dental, and fiber-optical applications.
- One of the colorants used for cubic zirconia and glass, providing yellow or red coloring. Glass containing holmium oxide and holmium oxide solutions (usually in perchloric acid) have sharp optical absorption peaks in the spectral range 200–900 nm. They are therefore used as a calibration standard for optical spectrophotometers, and are available commercially.
- As a result of its special magnetic properties, holmium is used in alloys for the production of magnets and as a flux concentrator for high magnetic fields.
- Holmia (holmium oxide) is used as a yellow or red coloring for glass and cubic zirconia.
- Good neutron absorbers and are used in nuclear reactor control rods.
- Used in solid-state lasers for non-invasive medical procedures treating cancers and kidney stones.
- Considered to be of low toxicity.
Source: Wikipedia, https://en.wikipedia.org/wiki/Holmium#Applications