GMS Field Trip February 2026

GMS Field Trip
Copper Ore, Slag, Sericite after Staurolite in Tennessee
Saturday, February 7, 2026

As members gathered to listen to Charles’ safety talk, a brisk breeze blew in and we scrambled to add more layers to combat the cold, becoming walking parfaits (not onions – I don’t like onions even if they are a better metaphor here). Forecasts indicated highs in the mid-30s, but as it turned out, except for the chill we got that morning, we only experienced a few chilly moments the rest of the day. It wouldn’t have mattered anyway; none of us cared – we were so excited to collect!

After caravanning to the collecting site, we met up with site personnel, then continued on to the first location. There were piles of partially processed copper ore just waiting to be perused. (It is important to note that the piles were placed there by the property owner specifically for us.) Members have cut open specimens collected during past trips to reveal solid copper, so that was the prize du jour. The best way to know if you have copper is to cut the rock open, so we collected pieces to cut later. In the meantime, juniors were having fun breaking rocks. They found some beautiful colors inside – green, blue, and red. At first, I though the red was iron that had not oxidized, but after seeing a few more examples, I realized the red was tiny crystals. Suddenly, the prize du jour was red crystals! One member said it is probably cuprite. After some quick research later, his identification seems very likely. Because people were excited by the new find, we stayed a little longer than usual to give everyone a chance to look for red crystals.

Next, we visited an enormous slag pile. Slag is a by-product of ore processing. It is often glassy, but in this case, the slag is mostly iron. Members had a lot of fun collecting oddly shaped slag pieces as well as a particular pattern we call “slagon skin”, a portmanteau of slag and dragon. My understanding is that it came from the days when a special breed of copper smelting dragons called slagons breathed fire on the copper ore to melt it. Their work was hot and made them so itchy they would roll around on the slag piles for relief, leaving behind bits of dragon dandruff.

The last location of the day was in a wooded area where members searched for pseudomorphs. A pseudomorph is formed when one mineral replaces another mineral and the new mineral takes the crystal shape of the original mineral. Their names reflect their origins as “new mineral after old mineral”. In our case, it was sericite after staurolite. Sericite, a mica mineral, replaced staurolite, a metamorphic mineral, during retrograde metamorphism, when temperature and pressure were lower than they were when the staurolite formed. Some of the specimens we find are partially replaced. They have bits of staurolite or a staurolite core surrounded by sericite. Most of the specimens have tiny almandine garnets embedded in them that are often seen on the surface as dark bumps.

On a prior trip, one of our junior members found a great spot where he pulled out specimen after specimen, and he did the same thing again on this trip! He found several large hand-sized crystals, as did other members.

There are piles of dirt and large ditches that were dug by the owner to make it much easier for us to search. At the edge of the woods, specimens are in soil that contains a lot of red clay, giving the sericite an orange brown appearance. Deeper in the woods, there is pile without much red clay, so the specimens are mostly white. Where the white specimens are found, there is also an accessible vein of grainy sericite, so our friends from the International Sand Collectors Society were thrilled to collect some sericite sand.

Everyone had a great time and went home with plenty of goodies. None of this would be possible without the incredible generosity of the property owners. They have gone above and beyond to provide places for us to collect. They always welcome us warmly to their unique geological area, and they make sure we have plenty of fun things to see and collect. Thank you! Thank you! Thank you! We cannot thank them enough for providing us with so many special opportunities. Thank you to members for not only showing me their specimens to photograph, but also for giving pieces to Charles and to me and members. They followed the rules flawlessly and were eager to thank the property owners. And, as always, thank you to Charles for arranging and running this fantastic trip!

Lori Carter on behalf of Charles Carter
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