Willoughby: Miners as Michelangelos of the underground
August 11, 2018
Aspen's miners used brains as much as brawn for backbreaking blasting work. To drain water and ease ore cart movement, they drove tunnels with a slight grade. They sculpted smooth-sided tunnels that adhered to specific dimensions and turning angles.
Although some passageways extended just as wide as the ore vein they followed, many tunnels attained a standard: 5-feet-wide, 7-feet-high, with relatively smooth and consistent walls and ceilings.
Most of the time, a team of two miners would drill holes at the end of the tunnel, pack them with powder, and then set off an explosion. The blast fractured rock and left a pile on the tunnel floor. It could take an entire shift to clean up the rock pile. In large operations, one miner cleaned out the rock and another shoveled the debris into an ore cart and trundled it outside.
An explosion required 18 to 24 holes, each about 14 inches deep. Here is where the brains worked overtime, the spacing of holes mattered. The rock type, turn of the tunnel, the slight grade and other factors determined the placement of the holes.
A miner drilled "cut" holes that took out rock in the center of the tunnel. Some holes were known as enlargers. These expanded the hole the cutters had made. Other holes, relievers, did not hold powder. These allowed rock to expand. "Trimmer" holes, near the edges, smoothed a tunnel's sides.
A miner did not set off all of the holes at the same time, because the order in which the powder fired contributed to the outcome. Each hole held a blasting cap, the highly explosive material that set off the powder. And each cap attached to a fuse, a length of combustible rope. By adjusting the length of the fuses, a miner controlled the firing sequence.
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In an explosive technique called "lifters," a miner caused fractured rock to fall and move a slight distance from the end of the tunnel. They drilled blasting holes near the bottom of a tunnel's end, and — by a few short seconds — they set these off last. If all went as planned, the final blasts would lift up rock and deliver it into a pile a few feet away from the tunnel's end. This technique made cleaning up, so-called "mucking," easier. To avoid catching a shovel on a rough spot, muckers would lay metal or wood sheets on the tunnel floor to catch the rock fall.
Lifters did not always go as planned. Holes at the very bottom of a tunnel's end often stood in water, and wet powder did not explode.
For mining, as in any business, timing is everything. All this work would advance a tunnel about a foot. And many mines could support only one shift. Water, time to erect timbering and the hardness of the rock may slow tunnel advancement.
Miners, underground sculptors, shaped solid rock into tunnels. Rather than wield a chisel, as did Michelangelo, Miners hefted dramatic dynamite. At the end of his life, Michelangelo gained fame by releasing human-shaped forms from within a white marble block. At the end of a day, miners measured achievement in terms of empty dark space.
Tim Willoughby's family story parallels Aspen's. He began sharing folklore while teaching Aspen Country Day School and Colorado Mountain College. Now a tourist in his native town, he views it with historical perspective. Reach him at firstname.lastname@example.org.
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