GMS Field Trip

GMS Field Trip
Talc, Serpentine, Hydroxylapatite in Georgia
Saturday, January 16, 2016

Dr. Bill Witherspoon, co-author of “The Roadside Geology of Georgia,” and geologist Terry Vines did presentations about the geology, mineralogy, and mining history of the old quarry we visited. Dr. Witherspoon explained how the geology of the area was formed, all the way from before Pangea to the present. He explained that the serpentine in the quarry is ultramafic and is actually a piece of the Earth’s mantle. Terry Vines showed us pictures of the quarry from some of his earlier adventures there many years ago and showed us examples of the minerals that can be found in the quarry.

The quarry was famous for the beautiful dark green serpentine mined there. Even though it was serpentine it was called marble and was used for decorative interior finishes. The quarry was worked from the late 1800’s to around the early 1920’s until the cost of extracting the material was no longer economically feasible.

Terry said that there were two pits and even the biggest was not very big, maybe 80 by 40 feet, but it was incredibly deep. He said at one point the Georgia Marble Company considered working the site, but soon discovered that the depth of the pit plus the difficulty of removing blocks from so far down was so costly that they could ship serpentine all the way from Italy and process it in here in Georgia cheaper than they could extract it from this quarry.

As we stood looking over what remains of the quarry, we saw some large bolts poking up from a heavy concrete slab. Terry explained that they once held the derrick that hoisted the large blocks from deep in the ground. Once the quarry ceased operations, the derrick was released from the bolts and now lies within the depths of the void that once yielded the beautiful blocks of serpentine that made the quarry famous.

The quarry is also famous to mineralogists because it is the type locality for hydroxylapatite. Some mineral collectors have hyrdoxylapatite in their mineral displays, but we all have it in our bodies -- in our bones and teeth. Another curious place where hydroxylapatite crystals are found in the human body is in the pineal gland in the brain. Small calcifications are called corpora arenacea or “brain sand”.

Armed with our knowledge of the quarry plus its geology and mineralogy, we hiked right into it. Once we were among the blocks still scattered about, everyone found a spot and started working away. Some beautiful pieces of green foliated talc were quickly extracted and it wasn’t long before people began finding hydroxylapatite. That was surprising because so many people have searched for hydroxylapatite here over many years and considered themselves lucky to find even a few small crystals after a great deal of work. Yet several field trip attendees not only found hydroxylapatite, but they found some spectacular specimens!

I think everyone who wanted serpentine and talc definitely got as much as they wanted. Many people also found another mineral, magnesite (var Breunnerite). And there were some nice magnetite crystals found as well. Thankfully, Dr. Witherspoon and Terry Vines were on hand all day to help identify specimens for everyone.

We found a lot and we learned a lot. We were incredibly fortunate to be able to visit this location. We owe many thanks to the property owners who allowed us to visit the site. They were very cordial offering their facilities for the presentations and even provided coffee and donuts. Many thanks to Dr. Witherspoon and Terry Vines for sharing their knowledge with us during their presentations and in the field. And, of course, thanks to Charles Carter for working diligently to make this trip possible.

Note: Because the location is actually rather small, the trip was limited to only 25 people. But so many people responded that Dr. Witherspoon and Terry Vines graciously agreed to do two sets of presentations so we could have another group of 25. There were several people on the waiting list too, but because people who couldn’t make it were quick to let us know, a handful of people on the waiting list were able to come. So the next time a trip is limited and fills up quickly, don’t give up. There is always a chance you may get to go.

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