GMS Field Trip September 2024

GMS Field Trip
Metagranite with Blue Quartz in Georgia
Saturday, September 21, 2024

When you are standing in a quarry surrounded by a pile of boulders, rocks that are 1.2 billion years old, you can’t help but be a little awed. When you squirt a splash of water on the rocks and they transform from every day gray to magical blue, you know you are in a truly special place. We were in the quarry to look for metagranite, i.e., metamorphosed granite. In particular, we were looking for metagranite with large white microcline feldspar crystals surrounded by coarse gray plagioclase feldspar and thin lines of shiny black muscovite mica – all best-supporting players to the star of the show – beautiful blue quartz. You can thank tiny titanium minerals for the blue color, and all you need to tease that color out is a spritz of water or, after you get your rocks home, a quick face polish.

Seeing the blue color appear never gets old, and I especially like to be there when someone has their first encounter with such a satisfying moment. So, I watched as members perused the piles with their squirt bottles and sprayers, all decked out in the proper PPE (personal protective equipment) including hard hats, safety glasses, sturdy footwear with ankle support, and high visibility safety vests. Pump sprayers were especially helpful because you can spray a good swath of rock with one squeeze of the trigger. Juniors, thrilled with their finds, proudly showed me their favorites pieces. Blue quartz was here, there, and everywhere, so it was easy for everyone to get their fill quickly.

Then, we turned our attention to the pyrite. It was mostly massive, sometimes lots, sometimes dots. Either way, it was shiny, fun to find, and really hard to photograph! We were also drawn to some rock with a lot of garnet that gives it a reddish-purple color. When we found this rock together with the metagranite, we usually found garnets in the metagranite side. The garnets were deep red, not terribly distinct, but they were there, and they were fun to find too!

The most surprising find of the day was purple fluorite. On a previous trip to the quarry, members spotted some fluorite in a boulder just as we were leaving. It was too hard to extract, so we reluctantly left it behind. The fluorite from this trip is destined for the GMS permanent collection courtesy of Dakota, the member who found it.

It was another great day in the quarry! We got a ton of pretty rocks, perhaps truly a ton! A trip like this would not be possible without the generosity of quarry personnel. They shared their Saturday morning with us to keep us safe and help us find beautiful rocks. We can’t thank them enough for all the wonderful things they do for us. Thank you to members who were so nice to share with other members, go out of their way to bring specimens to me to photograph for this report, and sent pictures to me later. As always, thank you to Charles for arranging this trip and for bringing snacks and water to keep us fueled up and hydrated.

Lori Carter on behalf of Charles Carter
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