The falling slab of rock that fatally injured a worker at the Galena Mine Friday was 4 ½ feet long by 2 ½ feet wide and 2 feet thick, federal investigators said. The Mine Safety and Health Administration continues to investigate the rock fall that claimed the life of Timothy A. Bush. Bush, 29, and his partner were working around loose rock when the accident occurred Friday morning. Bush was a former All-American defensive end for the University of Montana’s football team. He worked as contract miner at the Galena Mine near Silverton, Idaho, for United Mine Services/Becky Kramer, SR.