Neodymium - the most popular of rare earth metals

Neodymium - the most popular of rare earth metals

Neodymium metal is generally very well known, compared to it's cousins from lanthanides row - ask a random person about neodymium and they will probably at least recognize the name from somewhere, whereas thulium (Tm), gadolinium (Gd) or dysprosium (Dy) would most likely be a different story.

Pieces of neodymium metal under paraffin oil.

The main reason why is not the metal itself, but neodymium magnets, which will be talked about a bit later. Pure neodymium in it's metallic form is a shiny graish-yellowish-silver metal, which oxidizes rather rapidly on air, firstly getting covered with a dull black coating, which as time passes flakes off into what looks like a pink colored dust that serves no purpose in keeping the metal from further oxidation. 

The pink dust is Nd2O3, neodymium oxide that is often utilized in ceramics or glass making.

Neodymium glass bottle.

Nd3+ doped cubic zirconia stones

When added to glass, neodymium on +3 oxidation state dyes it purple-violet color that turns sky blue under fluorescent light. Similiar coloring can be observed on synthetic zirconia stones. Those look lighter and clearer than the traditionally dyed purple zirconias doped with manganese (Mn) ions.

Small cylindrical neodymium magnets in a jar.

Neodymium, sometimes called also rare earth magnets (that groups contains also Sm-Co magnets), are an alloy of iron, neodymium and boron. Due to their brittleness, these magnets are usually coated with a thick layer of nickel (Ni). An addition of dysprosium (Dy) can also be used to improve such magnet's resistance to demagnetisation. 

Nd2Fe14B magnets are currently the strongest permanent magnets available and can be purchased in many different sizes. Small 2x2 cylindrical magnets, like the ones pictured, are popular among 3D printing enthusiasts for adding magnetic locks or creating satisfying fidget toys etc..