Object destruction in unity?

I’m trying to create a full game styled similarly to a mini game I like. However I now need to be able to mine rocks or stone. I am using the standard FPS controller and a child axe for the player so what I want when I left click is the axe to swing forward and then back and the rock to loose some health. I also want the rock to take damage only when the player is right next to it as there will be many of these rocks around. So the script needs to work with multiple rocks. Does anyone know a solution?

Can someone please help with this?