Updated 3:34 p.m. ET
MULLAN, Idaho - A remote-control digger has arrived to help rescue workers advance more quickly toward a trapped Idaho silver miner.
But progress Monday may still be slowed by boulder-sized rocks and time-consuming safety work to shore up tunnels from further collapse.
Crews working to reach Larry Marek, 53, have so far dug through 37 feet of earth in the Lucky Friday Mine following the collapse more than a mile underground on Friday.
That's about half the 75-foot-long, 20-foot-wide (23-meter-long, 6-meter-wide) cave-in area.
The remote mucker can move between one to 3 1/2 meters of rock material at a time, but workers still need to shore up the excavated area behind it with timber.
A spokeswoman with mine owner Hecla said that "timbering" the mine was a time-consuming safety measure.
The roof of the tunnel collapsed about 5:30 p.m. on Friday, trapping Marek. Officials have not had contact with him and don't know his condition. He is a 30-year mining veteran, 12 of those years have been with Hecla.
The digging machine a front-end loader modified for mining and called a mucker had been transported inside the mine and will go into operation, allowing workers to work faster and more safely.
"The remote-control mucker has been sent underground and is being reassembled. It is expected to be operational during the day," the company said.
The machine will move material "without needing all the additional ground support to ensure the safety of our rescue teams," the company said.
"In the meantime, rescue crews continue to safely advance and progress on the removal of material," the company said.
Marek and another worker had just finished watering down blasted-out rock and ore when the collapse occurred about 75 feet (23 meters) from the end of the 6,150-foot (1,875-meter) deep tunnel, according to the company. Marek became trapped but his companion escaped. Family and media reports have identified the other worker as Marek's brother.
Officials say it's unclear if the entire 75-foot section collapsed, or only a portion of it, possibly leaving the miner trapped on the other side.
Hecla said all mining activity has been halted for the rescue effort. Officials said they will focus on how the collapse occurred once the rescue is complete.
The mine employs roughly 275 workers, about 50 of whom were underground in various parts of the mine when the collapse occurred, company spokeswoman Melanie Hennessey said.
On its website, Hecla describes itself as the oldest U.S.-based precious metals mining company in North America and the largest silver producer in the U.S. It is headquartered in Coeur d'Alene, Idaho. Hecla currently produces silver from two mines, Greens Creek and Lucky Friday, a mine that has been operational since 1942 and is one of the nation's deepest underground mines.
The mine is tucked into the forested mountains of Mullan, a historic mining town of 840 people. Like mining areas around the nation and world, it's not immune to accidents, some of them tragic.
Last June, a miner was killed in the Galena Mine in nearby Silverton after a rock slab fell on him.
And in 1972, 91 miners were killed in a terrible fire about 3,700 feet underground inside the Sunshine Mine between Kellogg and Wallace.
Hecla appears to have a good record of health and safety at Lucky Friday.