Lithium metal from a supermarket

 Lithium metal from a supermarket

Lithium (Li) is a metal that is rather sought after by collectors - at least in it's pure, unoxidized form, as just a couple seconds of contact with atmospheric air is enough to turn it into an oxidized mess. Lithium is also incredibly difficult to keep clean even in seemingly inert environments as it's prone to reacting with nitrogen gas most other metals are completely unreactive to in normal conditions.

10x40mm borosilicate ampoule with 0,2g of Li.

When covered by mineral/paraffin oil, Li is fairly resistant to atmospheric oxidation due to low permeablity of air through a layer of oil. Unfortunately, lithium has another trick up it's sleeve - it's also incredibly light, being around two times less dense than water and said oil or over 42 times less dense than the densest stable element - Osmium (Os).

This property causes lithium metal to float on the surface of anything that might try to cover it, exposing itself to air. These are precisely the properties that made me buy a premade ampoule in addition to my self-made sample.

My trick to keep the oil covered metal in a relatively acceptable condition was to insert a piece of sponge into the neck of my jar and to fill everything with oil to the top - this way there was a physical barrier that prevented lithium from floating, while, being saturated with the medium, it also protected it.

Lithium metal pieces under paraffin oil.

That being said, pure lithium metal in pieces or wire is not easy to source locally, so sacrifices often have to be done and other form of the metal used. In the form of foil it can be found in batteries - AA type batteries (the lithium ones, of course) contain a whole roll of the foil, while small button cells have only a bit of it at the bottom. In my opinion however, you will be better off just saving them as separate samples, because cutting them up to free the piece of foil is not only rather unsafe, but also will result in something far from a good looking sample.

Lithium 3V button cells.

A chunk of lepidolite.

An additional sample I got because of the interesting looks was a piece of lepidolite mineral. It's an ore of potassium and lithium with an impressive formula K(Li,Al)3(Al,Si)4O10(F,OH)2. Lepidolite is a mica mineral, meaning that it consists of multiple thin flakes that sparkle nicely but, unfortunately, it also crumbles easily. As a bonus, lepidolite is also an important source of the incredibly rare metal rubidium (Rb), which tends to substitute potassium in it's structure.