MineGates Inc - Grandview and Last Chance Mines, Grand Canyon National Park

Grandview and Last Chance Mines Gating Project
Horseshoe Mesa, Grand Canyon National Park

This project was made possible with the generous support of the mining company Freeport McMoRan.

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Located 3,000 feet below the South Rim of the Grand Canyon are the historic copper mines named the Grandview Mine and the Last Chance Mine. The upper part of the photo shows the Grandview mines, and the lower right hand corner of the photo shows the waste rock dump of the Last Chance mine. These mines were first staked in 1890 by prospector Pete Berry. The ore from these mines was hauled out of the canyon daily by a string of mules up the Grandview Trail. Note the mule team in the upper left hand corner of the photo. The ore from these mines was very high quality with some samples exceding 70% pure copper. But due to the high cost of moving this ore from such a remote location, the mine ultimately closed by 1907.

Today there are only ruins and scattered debris of this hundred year old mining works. The trail from Grandview point down to Horseshoe Mesa is the first historic feature that you will notice. It was built by the miners for the mule teams to haul bags of copper ore attached to the backs of each mule. Steep section of the trail were paved with rocks so that the mules would have good purchase on the trails. Down on the mesa are the ruins of buildings that the miners lived in. Most of these ruins are not much more than rock footers for tent and wooden structures, but one stone building along the main trail still stands roofless with it's fireplace chimney staking claim over this historic mine site.

Grandview & Last Chance Mines, circa 1900

Collapsing Tunnel in Grandview Mine

After 100 years, many of the mine tunnels and shafts have collapsed or have become quite unstable. Notice in the photo that the right tunnel is clear, but the left tunnel has dumped a large section of rock and dirt into the tunnel. The miners would install wooden shoring in mine tunnels at locations where they found loose rock. Over time this shoring rots, detiorates, and collapses sealing the tunnels.

Geologically, this mine site was formed in a formation called a Breccia Pipe. A Breccia pipe often starts out as a cave void that collapses to form a sinkhole full of broken rock or "breccia". This sinkhole acts as a natural drain that collects minerals that are tranported by water to concentrate at the bottom of the pipe. This is where the miners find their highest concentration of ore. This formation will also sometimes collect radioactive minerals as it did at the Grandview mine.

Many abandoned mines are ideal habitats for bat roosts. Pictured is one of the Grandview mine adits (mine tunnels that itersects the surface) that has nearly collapsed shut, but fortunately still has a small entrance that is just large enough for bats to fly through. Over ten years ago, Dr. Scott Altenbach conducted bat surveys and recommended bat compatible closures at this site. Building on this work, later biological surveys of the mines by BCI (Bat Conservation International) and GCNP (Grand Canyon National Park) biologists documented important bat colony roosts of Townsend's Big-eared Bat (Corynorthinus townsendii). This species of bat was found throughout the mines and plays an important part in the ecosystem of the the local area.

Considering the multiple criteria of protecting bat roosts, supporting on-going bat research, preserving historic mine resources, and promoting visitor safety; the GCNP decided to install bat-friendly gates on three of the mine entrances. After many months of preparation, gate manufacturing and site documentation the gates were installed on Sept 19-20, 2009.

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Collapsed Adit Entrance used by Bats