These are cool! These are little slices of noble shungite, most commonly to stick on your mobile phone or computer. They have the sticky adhesive already on them, you just need to peel the paper backing off them.

Shungite is one of the more famous stones, a carbon based one often used in water as a purifier.

The round slices are a little under 2cm in diameter, and the rectangular are roughly 1.5 x 2.5 cm.