Utilize the input text as a context reference, choose the right relationship between Codelco and copper from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

The world's largest copper producer Codelco said that operations were back to normal at a northern Chile mine after a brief stoppage during a week-old strike by contract workers.

Answer: product_or_material_produced