Thousands of unstamped pennies bound for the U.S. Mint in Philadelphia spilled over the northbound lanes of I-95 near the Route 141 interchange this morning when a big rig flipped across the three northbound lanes shortly before 2 a.m. and caught fire. The pennies spread across the roadway. The driver of the truck was treated at the scene for minor injuries.
The blanks, referred to as planchets at the mint, tied up traffic for at least eight hours.
If any copper thieves were thinking about a heist, the U.S. penny hasn’t been made of pure copper since 1837. Minters switched to bronze (95 percent copper and five percent tin and zinc) in 1837.
They changed to 88 percent copper and 12 percent nickel in 1857, giving the penny a whitish appearance.
From 1864 to 1962, they switched back to bronze, except for 1943, when the war effort limited the availability of copper and pennies were made of zinc-coated steel.
A rare occurrence during the switchover resulted in one of the most valuable U.S. coins – the 1943 copper-alloy penny. Only 40 are known to remain in existence. Coin experts think they were struck accidentally when some copper-alloy blanks were still in the hopper when production on the new steel pennies began.
That 1943 penny is one of the most sought-after items in American numismatics, according to the American Numismatic Association. The first one offered for sale brought more than $40,000 in 1958. One sold for $10,000 in 1981. The highest price paid was $82,500 in 1996.
Because of its value, counterfeiters have tried coating steel pennies with copper and altering the dates of other copper-alloy pennies.
In 1962, minters removed the tin and made pennies of 5 percent zinc and 95 percent copper.
Then, in 1982, they switched to the current mix of copper-plated zinc – 97.5 percent zinc with a 2.5 percent copper coating.