99.99% of all modern spark plugs are "copper core". The iridium, platinum plugs etc are named because of the different metals the are on the ground strap and center electrode, but still have a "copper core" that is inside the porcelain part of the spark plug.
This is from the NGK site. This is for a 2012 RAM 5.7 engine as a upgrade from the stock OEM plugs.
NGK 97606 PLZFR5B-13EG Double Platinum Spark Plug
NGK's Laser Platinum
Series Plugs Provide High Ignitability and Longer Service Life.
Laser Welded Dual Platinum
Surfaces Ensure Slow Wear Rate Providing Stable Idle, Superior Anti Fouling, Improved Fuel Efficiency and Lower Emissions.
- Trivalent Metal Plating Provides Superior Anti-Corrosion and Anti-Seizing Properties
- Corrugated Ribs Prevent Flashover
- Pure Alumina Silicate Ceramic Insulator, Provides Superior Strength and Better Heat Transfer
- Copper Core Aids in Heat Removal
- Triple Seals Prevent Leakage