Police say the two victims at Los Reyes mine were 24 and 40 years old, and Monday was their first day on the job. A third worker suffered an eye injury.
Preliminary reports suggest the accident may have been caused by a premature dynamite blast.
The National Geology and Mining Service says the mine was illegal and unregistered. Agency official Mariano Garrido says, "We did not know it existed."
Oversight of mines is spotty in Chile's vast, remote Atacama Desert.