The Incendiary Mine I is a supply consumable which is randomly available from supply boxes. It always comes in a stack of 3 and is not stackable further.
Once deployed, the mine would hover and spin on the spot until an enemy comes into contact. If they are not triggered, they would spontaneously detonate after a few minutes.
Despite the description, it hits much lower than that, as shown in the image. It takes several seconds to deploy.