MashGet

The giant Rio Tinto Borax mine in Boron locked out about 540 hourly workers Sunday after the employee union refused to ratify a new labor contract.

The lockout began at 7 a.m. as miners showed up outside the gates and were told they couldn't come in. Replacements were brought in to do their jobs.

"It's obviously a drastic measure and I am well aware of the fact that this has very real consequences to our employees. It's not a bully tactic, but it's our only real alternative," said Dean Gehring, general manager of the mine.