Unseen treasures of Michigan

Unseen treasures of Michigan.

Geology has always been an interest of mine. This past summer I went on a trip to the Upper Peninsula, guided with only a topographical map and a GPS. What kind of trip was this? It was a search for the hidden treasures of Michigan. These treasures, or rocks, are a gift left by nature for us to find. To the average person these are just rocks, but to the geologically aware they are more than just that. Each rock has a story to tell, and some are rather valuable. So let us begin this brief journey into the UP, and explore some of the specimens I collected this past July.

These two rocks may look like best friends, but it is far from that. They battled it out in a turf war billions of years ago. To the left is Mesnard Quartzite, which is a metamorphosized form of quartz. To the right is Mona Schist, a metamorphosized form of the rock Shale. Metamorphosized rocks are formed under the conditions of extreme heat and pressure. These two rocks collided with each other and formed a fault in an ancient mountain range (Yes, Michigan did have mountains at one point). Over time they have been weathered away to smaller rock formations. I collected these rocks off of a rock formation on US-41 in Marquette.

There are also interesting rocks to find in the small town of Ishpeming. After searching through the town I was able to find a small path located off a side street. This path leads up a hill called Jasper Knob. This location is called “Michigan’s Greatest Secret” by the people in the town, and is composed of a rock called banded Jasper. These are just a few of the specimens I collected there.

Ishpeming is home to another secluded secret. After going north through the town, I found the abandoned Ropes Gold Mine’s dumping area. This dumping area consists of leftover rocks that held no value to the miners at the time. Geologically, these rocks are highly valuable. Serpentinite was scattered all around the dumping area. The real reason I visited this location was to find a rare form of Talc. Talc is a soft greasy rock, and it is used in powder. According to the book I was following, a rare form of Talc could be found here. After much searching I found a small sample of what I was looking for, Green Talc. Mixed in with this Green Talc is asbestos. Asbestos is common to find in Talc, because they are related geologically.

(Serpentinite)

(Green Talc)

Eagle Harbor, a town in the Keweenaw Peninsula, is home to Brunette Park. Jacobsville Sandstone is found out in the water at this park off of Lake Superior. Sandstone is a rock that consists of sand hardened together. Jacobsville Sandstone is unique to the Upper Peninsula, and is known by its distinct pink color.

The Keweenaw Peninsula is home to many abandoned copper mines. In various spots you can find the old dumping areas for these mines. The Iroquois Mine’s dumping area is located off of a dirt road in Mohawk. Hills of discarded rock lay upon the ground here. After some exploring I

was able to find copper, calcite, and even Epidote in the rocks here. Using a metal detector I was able to find rocks with copper in them. Calcite is a mineral that forms by water getting trapped inside a rock. It is a plain white color most of the time, but sometimes it can form as a green mineral. Epidote is an olive green mineral, and is a variation of the gemstone Jade. It is very rare to find in these rocks, but luckily I was able to find a specimen of this.

(Copper in discarded rocks)

(Calcite in discarded rocks)

(Epidote in discarded rocks)

These are just a few of the rocks Michigan has to offer. Hopefully you have gained some insight after reading this. I had a thrilling experience finding these rock specimens, and it was a fun trip overall. I plan on going again in the spring, and showcasing even more of these unseen treasures of Michigan.

Please comment with any questions or feedback.