SANTIAGO, July 28 World no.1 copper miner Codelco halted operations Tuesday at its key Chuquicamata mine as a week-long contract workers' strike intensified, chief executive Nelson Pizarro said.
Refer to the input text as context and select the correct relationship between 'Chuquicamata' and 'copper' from the available options.
Options: position held, product/material produced, brand, operator