Crandall Canyon mine tragedy timeline
* Aug. 6, 2:48 a.m.: Crandall Canyon mine collapse registers 3.9 magnitude. Six miners trapped, four escape.
* Aug. 6, afternoon: Rescue crews enter a tunnel parallel to the one the miners are thought to be in, only to find it has collapsed.
* Aug. 8, 10 p.m.: A 2 1/2 -inch drill penetrates the mine from above, but a microphone lowered into the cavity picks up no sound.
* Aug. 10, 12:10 a.m.: First air sample from 2-inch borehole has 20% oxygen; readings at 1:45 a.m. have it down to 7.2%, a level too low to sustain life.
* Aug. 11, 8:15 a.m.: Camera is dropped down a 8 -inch borehole. Images reveal a "survivable space," but no other signs of life.
* Aug. 12, 2 p.m.: New video images show mining equipment, but no signs of the miners. Rescue teams prepare to drill a third borehole, targeting tunnels deeper in the mine where the miners might have fled.
* Aug. 14, 6:30 p.m.: Miners have recaptured about 750 feet of the collapsed fresh-air tunnel, leaving 1,720 feet to go. They have endured a number of mountain "bumps" that threaten cave-ins and force rescue teams from the mine.
* Aug. 15, 10:15 a.m.: The third borehole intersects mine; microphone detects no sound.
Aug. 16, 6:39 p.m.: Some 30 feet of the main tunnel collapses. Three rescue workers are killed, six others hospitalized. All rescue efforts are suspended.
* Aug. 18, 9 a.m.: Fourth drill hole penetrates mine. No signs of life.
* Aug. 22, 8:30 a.m.: Fifth drill hole reveals a 6-inch space in a tunnel filled with rubble.
* Aug. 25, 6 p.m.: Sixth borehole, which officials say will be the last, hits the mine. No air space is detected in a tunnel filled with rubble. Mine co-owner Robert Murray announces he is shutting down the Tower Mine outside of Price, citing safety concerns.
* Aug. 26, 3 p.m.: Federal mine officials announce a plan to sink a seventh borehole, this one in the "kitchen" where miners store their lunch boxes. Also, a robotic camera will be lowered into an earlier hole to search for signs of life.