With lights, raingear, helmets, and cameras, we entered the 936 foot long adit with the intention of taking lots of pictures and any crystals we could find. The pictures were easy, but we had to work to find crystals. Most of the tunnel was barren and dripping with water, but about half way back we started seeing color in the walls. Soon, we saw huge areas of blue, green, purple, yellow, and white. YES!!

The Last Chance Mine was opened around 1900 as a copper mine. The adit we entered follows a copper vein that is between 1 and 4 feet wide. Minerals present include chrysocolla, malachite, bornite, and pyrite. Azurite, chalcocite, and chalcopyrite are less common. The bornite, chalcocite, and chalcopyrite occur as disseminations and blebs in the vein quartz, whereas chrysocolla, malachite, and azurite occur as coatings on fracture surfaces. In a few places, chrysocolla occurs as veins 1 to 6 inches thick. Near the face of the adit, mottramite (lead vanadate) occurs as thin greenish-yellow coatings on vein surfaces.

Development work at the Last Chance mine consists of a 936-foot east adit, a 267-foot west adit, and a 540-foot vertical shaft. The east adit is on the east bank of the West Fork of the Washougal River. It bears S. 54° E. for about 500 feet, then S. 45° E. for 463 feet to its face, which is about 200 feet beneath the surface. Nine crosscuts, ranging from 10 to 40 feet in length, driven into the southwest wall of the vein encountered several quartz veins and stringers that parallel the Last Chance vein. The 540-foot shaft is at the portal of the east adit, and at 64-, 200-, 300-, 400-, and 500-foot levels in the shaft, drifts have been driven along the vein in southeast and northwest directions. The drifts range from 30 to 209 feet in length. The west adit is about 280 feet northwest of the east adit, and is on the west bank of the West Fork of the Washougal River. The adit follows the vein N. 60° W. for 267 feet.

We found an area on the ceiling that showed quartz crystals and spent some time there. After some preparations, we started in with hammers and chisels. The plates of quartz crystals we removed ranged from clear to white to purple. YES!!

After we were done and all of the crystals were cleaned at home, we found that half of the quartz was covered with other minerals: mottramite (yellow), chrysocolla (blue), and malachite (green).

For an old mine that's knee-deep in water, this is one great collecting site. We hope to collect here again. And again. And again.

Please note that there is an unmarked 540 foot deep hole near the entrance to the adit. This is not a place for children. Please don't trespass. A better idea is to write to me and I'll sell you a few samples from this mine.

To view the NWMMSG report and SEM photo on this site, see also:

http://members.tripod.com/~WTompkins/index-261.html

Bill Tompkins

Clackamas, Oregon