base metal 
noun
A common metal that is not considered precious, such as copper, tin, or zinc: cutlery was available in silver or base metals [mass noun]: most are made of base metal...
- Within these belts, gold mineralization is associated with rare metals, base metals, uranium, antimony, and mercury.
- Alloy steel, copper, lead, zinc and base metals are basic raw materials used in a variety of industries.
- Its focus is on gold but its portfolio also includes projects with potential for platinum group metals, copper, silver and base metals.