Spark plugs are at the centre of the ignition system on all petrol-based vehicles.
Some are copper cored as copper is a good conductor of electricity.
NONE have copper electrode tips, as they would burn out in about five minutes!
Some have steel electrodes, some platinum, and some iridium. Iridium is the best as far as longevity goes. Platinum has a lower melting point so it won't last as long.
Iridium can last between 75,000 to 100,000 miles in a car.
I am English, so centre is spelt wrong, well because... English