Eureka Tunnel/Stove Mountain Field Trip Report
We started this trip by meeting at a Park & Ride parking lot in Colorado Springs on Saturday morning. We had a couple members of the North Jeffco club show up, including Tom Miller, Kevin and K.C. Larsen, and myself. Most of the rest of the attendees were from the Colorado Springs club, and boy were there many of them. I didn't count the vehicles, but I would guess there were 12 to 15 cars/trucks.
After a long convoy to the area, we came upon a locked gate, which we were expecting, but what we weren't expecting was that the lock couldn't be opened because something was stuck in the keyhole. A few of the people guessed at what it could be: a broken key, a nail, a toothpick/stick, etc. Whatever it was, it wasn't letting anyone (i.e. us, the Forest Service, etc) in or out, so it was decided to break the lock and notify the Forest Service. That lock was stubborn! Hammers, chisels, a gad bar, and screwdrivers - you name it - everything was used. It was finally broken and the convoy continued to the first digging area, the Eureka Tunnel for zircon crystals.
After hiking down a couple hundred feet to the Eureka Tunnel opening, I was a little surprised at how small it was. I was expecting a normal sized mining tunnel, but it was a short tunnel that opened into a large "room" which then had two short tunnels opening from it. The overall tunnel length couldn't be much more than 50 feet. It was dark inside so we used flashlights to wander around, but because zircon fluoresces, many of us brought ultraviolet (UV) lights and used them more than the flashlights. When using the UV lights, lots of yellow specks lit up on the tunnel floor. These were either zircon dust, crystal pieces, or actual crystals. There was also a red glowing color in the UV light, but that was feldspar and not what we were really looking for. The largest zircon crystals that I saw, after emerging out of the tunnel into the sunlight, were only a few millimeters in size, but some of them were gemmy. Hiking to and from the tunnel, we found pieces of riebeckite on the ground. It is a black mineral that didn't seem to have any faces because it is so broken up. Maybe if we had hunted a little longer for it we might've found better specimens. I heard there was also some fluorite in this area but I never saw any.
Around 1:00pm we left that area for a pegmatite area on Stove Mountain. It was just a drive of 15 minutes or so to the northwest from the Eureka Tunnel. We all parked our vehicles and Ray then told us that there is good stuff "up there". We all looked up and saw this steep slope with a few boulders, grass and pine needles, along with the usual pine trees. We knew it would be tough climbing up there, but life's an adventure, right? Some people came up part of the way and did some surface collecting. Others, including myself, hiked up quite far.
I moved a lot of dirt and rock from under a tree stump and found a small pegmatite vein, but it was in solid rock, so I quit digging there. I saw some rocks that had rolled down from a bulldozer cut and found a few zircons in crevices on them. These zircons are much larger (1 cm) than the ones I found at the Eureka Tunnel, but they are not at all gemmy and have a grayish-brown metallic color. Still, they are nice specimens. On the way back a few of us checked out an area where there were signs of purple fluorite in several places, but unfortunately none of it occurred in euhedral crystalline form.
It was a nice day trip, and the weather was perfect. I think everyone found some zircons, at least at the Eureka Tunnel. Ray Berry, our trip leader, was very knowledgeable and a really nice guy. I would like to go back to that area again sometime and spend a little more time at both locations.