SPOKANE - Mining company officials and friends expressed confidence Thursday that a trapped miner could still be alive deep in the dark bowels of an Idaho silver mine as rescue efforts stretched into a seventh day.

Hecla Mining Co. employee Larry Marek, 53, has been trapped with little food and water - likely in the dark and in temperatures well over a 100 degrees - since late Friday afternoon when a tunnel collapsed in the Lucky Friday Mine.

Rescuers have managed to drill holes that provide air and drinking water to the area where Marek was last seen, a federal official said. But it's unclear whether Marek had communication equipment at the time of the accident and there has been no sign of him, even as a tiny camera inserted through a drill hole on Tuesday searches an open area behind the cave-in for him.

"We are 100 percent still focused on rescue efforts," said Melanie Hennessey, a spokeswoman for the company, which is based in Coeur d'Alene. "This is a strong individual that has experience ... We've seen people that have survived for long periods of time in such situations."

She pointed to people who survived after being trapped for long periods in recent earthquakes in Japan and Haiti.

Rescuers by Thursday afternoon had drilled almost halfway to where they believe Marek is trapped, with officials for Hecla Mining Co. pushing forward with fevered efforts to drill through solid rock toward where they believe Marek could have been trapped after the cave-in sealed him more than 6,100-feet down.

There is no firm standard for determining how long the rescue effort will continue, said Kevin Hirsch, the assistant western district manager for the Mine Safety and Health Administration, who is on the scene.

Marek's friends prayed he was still alive.

At a prayer gathering for Marek on Wednesday evening, friend Julie Trumble recalled the 1972 Sunshine Mine fire a few miles from the Lucky Friday that killed 91 miners. Two miners were found alive after spending eight days underground.

"And I keep thinking of the Chilean miners," Trumble said during the gathering, according to KREM-TV.

U.S. Labor Secretary Hilda Solis sent a message of support to Marek's family, the MSHA said.

Rescue workers are drilling and blasting their way through 220 feet of rock in an effort to reach Marek's last known location. They had advanced 101 feet as of Thursday afternoon, Hecla said in a press release. They began the escape path on Monday afternoon.

Rescuers are also busy drilling a third 2-inch hole into an open area behind the cave-in, where they hope Marek is located. Two earlier drill holes into the open area have allowed fresh air, water and a small camera to be inserted into the open area, known as a void. The camera has so far found no sign of Marek.

"We anticipate that we will continue to drill additional holes in order to gather information and better understand the open area," Hecla said in a press release.

The tiny camera was sent through a 180-foot hole created by a diamond-headed drill late Tuesday. The camera was loaned by Roto-Rooter in nearby Spokane, and is designed to detect clogs and leaks in pipes. It is not designed to give images of a large area.

Hirsch said it is hard to know which direction the camera is pointing, and depth perception is difficult so rescuers cannot determine the height and width of the void. The camera does not pick up sound.

It's too early to investigate the cause of the cave-in, Hirsch said.

"There is not enough information to make any type of determination and we haven't started any type of investigation," Hirsch said.

The main job of MSHA workers at the mine is to ensure safe conditions for rescue teams, Hirsch said.

Rescuers worked more than a mile underground for 12 hours at a time. The mine has shut down production to concentrate on the rescue effort.

The last fatality at the Lucky Friday was in 1985, according to MSHA records.

Metals mining is generally safer than coal mining, because of less dangerous gases, Hirsch said. But a lot depends on the efforts of the operator.

Marek, a 12-year Hecla employee, likely carried water, his lunch pail and protective equipment. He might also have air and water through the hoses attached to his hydraulic drill, longtime miners said this week.

Marek and his brother, Mike, had just finished watering down blasted-out rock and ore in an area called Stope 15, which has been mined for 14 years, Hecla said. That's when the ceiling collapsed about 75 feet from the end of the 6,150-foot deep tunnel, the company said. Mike Marek, who was working at the opposite end of the collapse from his brother, escaped unharmed.

The Marek family has not commented. Federal officials said many family members work at the mine.

Hecla is the largest silver producer in the nation, from the Lucky Friday and the Greens Creek mine in Alaska.

Lucky Friday, which has operated since 1942, is located in the forested Bitterroot Mountains of the Idaho Panhandle's Silver Valley. Reports on file with MSHA show the company has reported a dozen roof falls of various sizes since 2008, with a total of three workers injured.

The mine employs about 275 workers and 100 contractors. Working in tunnels that are hot and wet, miners drill holes in the rock faces, blast them to rubble and then drive the rubble to the surface to be processed.

The last miner to die on the job in the Silver Valley was former University of Montana football star Tim Bush, 29. He died of blunt force trauma after he was hit by a falling slab of rock in the nearby Galena Mine in June 2009.

These days, the Silver Valley is among the nation's largest Superfund sites, with toxic metals pollution that the Environmental Protection Agency says will take decades and hundreds of millions of dollars to clean.