The Clyde Forks Deposit was first staked by "T. Caldwell" in 1918-1919. I'm guessing this was Thomas Boyd Caldwell (who went by "Boyd"). His father (also Boyd Caldwell, just to keep things confusing) had, in January 1880, opened what became known as the Wilbur mine on the K&P south of Clyde Forks. As a widely invested entrepreneur and member of federal parliament, T. Boyd himself most likely remained in Ottawa or his Lanark riding sipping Scotch, while his hapless minions tramped around in the bush on his behalf doing the actual exploring.
As readers of my Wilbur posts will know, the geology along the K&P line is notable for its many mineral deposits--in particular of iron ore--and the region was surveyed extensively in the late 1800s and early 1900s for mine development potential. Other local deposits of interest include silver, gold, copper, antimony, mercury, and barite--all of which are found to some degree in the calcitic marbles at the Clyde Forks Deposit.
Now, before you grab a pick and rush into the bush, it's important to note that mineral claims are well staked across the region, including at this site. While I haven't checked exactly who currently owns the lease on this mine site, two claims were staked as recently as 1984 and probably remain on the books. Indeed, significant copper-antimony-mercury-silver-barite mineralization was identified at the site around that time. However, the deposits probably do not warrant commercial exploitation, which leaves this site as another interesting footnote in Lanark County history.
As Dr. Steve Brule says, "Check it out!"
The bush road leading to the mine site is overgrown, mud-holed, and rife with mosquitoes. Rather than ride it, I parked at a logging staging area and hoofed in the last few hundred metres with my GPS. The terrain in this area is lumpy and steep, with rocky outcrops and mixed hardwood forest. Not the easiest terrain to ride or hike across. I certainly feel for the surveyors who first came out here with chains and transits to take a bead on a claim.
Eventually you reach a clearing on crushed stone where it's obvious some kind of industry occurred. Here, the broken calcitic marble has not had time to weather and it stands in stark white contrast to the mossy rocks and general gloom in the surrounding woods. A campfire that seems to get regular use sits in the middle of the clearing.
On one side of the campfire is a large pit in the undergrowth. Some research identifies this as a test pit dug (probably by T. Caldwell's crew in 1918) to expose a mineralized barite vein. In fact, signs of several other test pits and trenches are visible in the immediate area. One carload of crude material from these pits was reportedly shipped to the U.S. for analysis.
Back on the opposite side of the campfire, a cool breeze emanates from a dark shadow behind the spruces. A closer look, and there is is: the mine entrance, or adit, at the base of the rock face--complete with a modern non-stick frying pan for intrepid visitors. Obviously this site sees regular visits.
The timbering at the entrance probably dates from 1969-1970, when the main exploration of the site was undertaken to assess the mineral potential. The location of the adit and the generally dry conditions in the area have helped to preserve the wood. Indeed, it looks to be in good condition, although I wouldn't bang on it. The rock appears to be very solid as well. A quick look inside is probably statistically safe.
My headlamp did nothing for me, since my eyes had insufficient time to adjust and I didn't think it was wise to hang around in the tunnel until they did. So I only looked in a few metres and took some pics with my iPhone on flash.
The workings are quite small. The tunnel extends straight in about 50 feet, bends slightly left and then proceeds about another 70'. At the bend a drift extends to the left about 15'. Twenty feet past the bend, a second drift extends left about 10 feet. The records (as shown in the pic below, taken from a petrographic study of the site ) indicate that grab samples of the barite were taken on the left wall near the tunnel entrance, near the end of the first drift, and near the end of the adit. The barite vein is apparently fairly obvious in these locations, although I was not equipped to identify it during my visit.
Near the entrance are some iron rods wedged into holes drilled into the rock. I'm exactly not sure what these were used for; maybe to provide a support for drilling or rock-moving equipment. Or maybe just a handy way to hang the rest of the kitchenware.
The petrographic study of the site  provides an interesting discussion of the mineral potential:
"An important feature of the property is the potential for gold mineralization in addition to the knownCu-Ag-Sb-Ba-Hg deposit.
"The prospect is similar to several marble-hosted, disseminated, gold-pyrite-tetrahedrite showings in the area [...] Gold mineralization, at these occurrences, appears to be related to the degree of pyritization and/or silicification in marble host rocks.
"In terms of the overall geochemistry and style of mineralization, the Clyde Forks Property is generally analogous to many large disseminated gold deposits in North America [...] such as Carlin, Cortez and Getchell in Nevada."
So, there we go: Once again, the marble geology of Lanark County provides an interesting dualsport adventure. And a connection to Nevada, no less.
1. Petrographic Study, Clyde Forks Deposit, Lavant Township, Southeastern Ontario. Jurate Lukosius-Sanders. June 1987.