Two interesting articles here and here regarding the association Thunor has with copper. I'd like to add some extra thoughts to these views. In regards to Wulf's post he mentions that he uses copper tools in the garden, I myself have used a copper tape which stops slugs and snails crossing over them. Like Wulf states, the copper carries a small electrical charge which shocks the slugs (or so the theory goes..)
We know copper is associated with Thunor/Thor,and he is described as having a copper red beard. Thor's belt, which is called Megingjörð, is itself a symbol of the electrical circuit. Sif who is Thor's wife is a corn and earth goddess - thus electricity (Thor) always seeks the earth (Sif).
The word 'copper' is a Roman term. The Anglo-Saxon word for copper was Ar or Ara. This came from the Germanic term Aes and in modern use evolved into our word ore.
Thunor has always been a god of the peasant and farmer. His symbol of the hammer is a workers symbol - and Thunor a true god and friend of the working man!