Mining the Christine Marie: Abrasive Rock

The two host rocks separate.

The jasper on the Christine Marie claim is in a steep rock slope about halfway down the canyon from the rim above. The host rock is labeled a welded tuff, and extends from the slope of the hill up past the cliff above to the pinnacle on the Amy Ellen claim; a distance of around 200 yards. The jasper formed in cracks in the tuff before it was in its present position. The entire hillside is a mixture of very large rocks (2-10 tons) and millions of small ones (1/2-5 pounds).

This rock is very abrasive. Because of the rock’s abrasiveness the rocks do not fall easily, but cling to each other. This quality contributes to the steepness of the area by not allowing rocks to erode downhill as fast. To illustrate this, it is possible to take two flat pieces of this welded tuff, place one on top of the other and tilt the pair of rocks almost 80 degrees before the top rock will fall off. Try this with most other rocks and the top rock will start to slide off with a tilt of a little over 45 degree

Gene holding the two pieces of abrasive rock.

The jasper in this deposit is scarce, but very good. A lot of rock must be carefully moved to collect a small amount of jasper. The abrasiveness of the rock takes a toll on your gear, as well. There were many days where a new pair of gloves in the morning would have one or two holes in the fingers by late afternoon. Using duct tape on your fingers was a common practice used to get more use out of a pair of gloves, or a little less wear on your fingers. I learned to buy a new pair of boots before I came out to the mine because a pair of boots lasts about a month working in this rock. I always use steel toed boots to protect my feet. After a month of mining Morrisonite, the leather would be worn off the toes of the boots revealing the scratched, shiny metal underneath.

Notice how tilted the rocks are, and they still stay together.

One very good thing about working in this rock was that it would always warn you when it was about to fall. Unlike other rock slopes which can give way with no warning, this rock will talk to you before it falls or gives way. The abrasiveness of the rock holds the pieces together until gravity becomes too much and you will start to hear small sounds. Soft sounding “ticks” and small creaks can be heard once in a while, and then more frequently. Through experience you come to understand when to get out of the hole you are working in and wait for the rock to cave in or get out of your hole and start the rock slide yourself, thus making it safe to work again.