How could mines work in space?

How could mine warfare work in a science-fiction space setting?

Open space makes fixed mines hard to hide and easy to bypass, but asteroid fields could conceal them and make an explosion warn defenders of an intrusion.

Concealment is the central problem for space mines. Water hides naval mines, whereas objects in open space may be detected at long range and bypassed in three dimensions. An asteroid field supplies natural clutter in which weapons could be hidden. An explosion there would also warn defenders that something had entered the field.