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.

One of several recent supply issues is a strike at a Codelco mine in Chile, which has prompted the world's top copper producer to stop offering spot refined copper to China for two weeks, sources said.

Answer: product_or_material_produced