GMS     The Georgia Mineral Society, Inc.
4138 Steve Reynolds Boulevard
Norcross, GA 30093-3059

GMS Field Trip

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So many rocks!

GMS Field Trip
Epidote and Grossular Garnet Xenoliths in Granite,
Pyrite, and Scolecite in Georgia
Sunday, November 4, 2018

In November, GMS members visited a quarry in Red Oak, GA that contains some fascinating geology. The area we visited has many xenoliths. The word “xenolith” is from the Greek “xenos” meaning foreign, and the Greek “lithos”, meaning stone, so it is basically one type of rock trapped in another type of rock. This usually occurs when magma rises through the earth’s crust and bits of country rock fall into the magma. Chunks that maintain their composition and are not completely dispersed into the magma are called xenoliths. At Red Oak, we saw many examples of metamorphic xenoliths in granite. The xenoliths contain epidote and reddish orange grossular garnet. We also collected some pink specimens, probably feldspar or calcite, as well as some pyrite. David Bruce found a spray of clear, thin crystals. Last year, Daniel Miller found a similar specimen and it was confirmed to be scolecite. A last minute find by Diana Poppelreuter had Juergen and Charles frantically trying to extract a chunk from a boulder as we were leaving, but alas, the specimen, possibly aquamarine, had to be left behind in its rocky abode. On the way out though, thanks to quarry personnel, Charles and I managed to retrieve a small boulder with good examples of xenoliths to put in front of the GMS building. It was a great day of collecting and everyone I talked to had a lot of fun.

Many thanks to the quarry personnel who patiently answered all of our questions and made sure we were always safe. And thanks to Charles for arranging this excellent geology trip.

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

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David Bruce found this specimen with radiating crystals that have not been identified yet
Photo by Lori Carter

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Example of the pyrite there
Photo by Lori Carter

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These small radiating crystals may be scolecite
Photo by Lori Carter

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Bob Dolezal got this subperb yard rock
Photos by Lori Carter

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We were pretty deep, but the quarry continued even deeper
Photos by Lori Carter

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Jane made piles of rocks to pick up later
Photos by Lori Carter

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Beautiful sample with grossular garnet crystals (orange) and epidote crystals (green)
Photos by Lori Carter

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Diana's last minute, possible aquamarine that had to be left behind
Photo by Lori Carter

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Last minute xenolith yard rock for GMS that Charles dubbed the "Racer X" rock

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