Lithium metal is a silvery-shiny material and it is the lightest of all metals, with only half the weight of water. Like many other elements, lithium metal reacts with air, but opposite to most of those hardly with oxygen, but preferably with nitrogen. Thereby Lithium metal quickly forms lithium nitride, Li3N, which makes a dark layer on the otherwise light silver surface. Lithium metal reacts with water producing Hydrogen gas, for that reason any contacts with water must be avoided!
Lithium metal is often used in disposable and rechargeable batteries, while lithium salts are used in medicine as treatment for mental disorders.
In the right picture a oxide free Lithium metal sample is showed
High Purity Lithium metal sample of 1 gram, shiny silvery pieces in labeled glass vial under mineral oil. Pure and Safe Lithium metal for element collection and laboratory. The mineral oil prevents, but it doesn't stops entirely, the oxidization of Lithium metal inside.