The reason the mint switched from copper to zinc is that the price of the copper ended up being substantially more then 1 cent. When the price of copper was high it actually reached the point it was profitable to get copper coins from the mint, melt them down and sell them as bulk copper if you did it on a large scale.

I found a calculator (http://www.coinflation.com/) that indicates that with today's price, the metal value of a pre-1982 coin would be $.014. And that is at rather depressed prices, during the pre-bubble spike it could have been double that.

Jay