GMS Field Trip

GMS Field Trip
Agate and Fossils in Tennessee
Saturday, November 11, 2016

Despite its on again off again start, this field trip ended up being a very good trip. After verifying our safety gear, safety training, and signing forms, we were escorted by caravan into the quarry. The high walls were really high!

The nature of quarries is very much like our friend Forrest Gump's box of chocolates -- you never know what you're gonna get. This time we got the good caramels, not the yucky bonbons. Right away we saw tiny chips of agate on the quarry floor (Diana even found some in the parking area!) Then the boulders began to reveal their goodies.

The agate occurs as nodules in the limestone. Much of the agate is brown to "reddish", though there are some yellows and brighter reds too. The desirable "Calfkiller" agate is considered to be the agate here that has lots of colors. I saw some color, but perhaps the best color was in two pieces that Ivy Edwards found.

There were several vugs with calcite crystals, dolomite, and possibly celestite. David Bruce and some energetic rockhounds managed to extract several vugs with matrix to be processed later.

Mary found some unusual dark, striated material that we were not able to identify. More and more of the material was found as the day went on, but still no identification. The next week at Fossil Section, Bill Waggener explained what they are -- stylolites (also styolites). They are formed by the dissolution of minerals under high pressure. Insoluble minerals fill in the voids caused by the dissolution and make the stylolites visible. In this case we are not sure what filled in the stylolite structures, so we still have a bit of a mystery to ponder.

Juergen and Diana Poppelreuter found some nice fossils including a superb gastropod. I noticed various marine fossils in what appeared to be glauconitic limestone. There were also some curious boulders that appear to have embedded calcite crystals.

The quarry people were exceedingly gracious in allowing us to collect in the quarry. They even gave us a huge piece full of agate to work on. We cannot thank them enough for this rare opportunity. Many thanks to Charles for his persistent efforts to get a field trip into the quarry and thank you to all of the participants who came prepared and followed all of the safety rules.

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