GMS Field Trip

GMS Field Trip
Massive Epidote with Grossular Garnet, Pyrite,
Xenoliths, and Granite in Georgia
Sunday, October 15, 2017

Bill Witherspoon, GMS member and co-author of The Roadside Geology of Georgia, started the trip by explaining the geology of the area. After the quarry manager gave a safety talk, Bill thanked him by donating a copy of his book on behalf of GMS to the quarry. Then, quarry personnel led the group to an upper bench in the quarry. We collected samples of granite, biotite mica, and saprolite there before going deeper into the quarry. In the next level of the quarry, we observed excellent examples of metamorphic xenoliths in the granite.

Massive epidote with grossular garnet was abundant. A quarry employee went to an off-limits area to get a bag of manufactured sand for me and Charles got a sample of core boring silt and sand for me! Several collectors found pyrite and an unidentified purple mineral. We know it is not amethyst or quartz because it is easily scratched with a metal knife. Possibly fluorite? Daniel Miller found a pocket of unidentified crystals that will need more research, too. Bob Dolezal found an orange mineral that may be either grossular garnet or chabazite. Susan Oltman’s students enjoyed studying rocks from the quarry the very next school day!

Many thanks to the quarry personnel for welcoming us to the quarry, teaching us about the operation, hauling rocks for us, providing cold drinks, and making sure we were safe plus Charles for setting up this fascinating trip!

Lori Carter
On behalf of Charles Carter, GMS Field Trip Chair
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