What is the relationship between 'Chuquicamata' and 'copper' in the context of the input sentence.
Options: director/manager, distribution format, product/material produced, developer

The Chuquicamata mine, located 1,650 kilometers (1,000 miles) north of Santiago, produces around 339,000 tonnes of copper per year, making it one of the company's most productive sites.
product/material produced