I believe that this 1965 5 ore from Norway was struck on a planchet made from improperly mixed metal. I'd like to think that the northern lights are dancing around it.

That's a fantastic coin. It certainly does look like the Northern Lights.

Oh I love it!

That striated effect is often found on UK bronze pre-decimal pennies and, as you correctly mention, is caused by poor metal mix. Your one however has developed rather dramatic colouration to it which adds to rather than detracts from the coins subject. Nice find!