GMS Field Trip January 2023

GMS Field Trip
Various Rocks and Plant Tour in Georgia
Friday, January 6, 2023

With great pride, Elberton, Georgia carries the nickname “Granite Capital of the World”. It is a fitting name because Elberton sits atop a granite deposit that is approximately 35 miles long, 6 miles wide, and 2 to 3 miles deep! In addition to numerous granite quarries, Elberton is also home to numerous processing plants. The plants process more than Elberton granite. They process material from all over the world.

Our trip started at one of those plants. We saw water jet cutting processes that are computer controlled and use lasers for alignment and garnet sand for cutting. Workers showed us what they do and how the equipment works, then they answered all of our questions. There were several slabs set out for us so we could see the difference between the surfaces before and after polishing. Since the material comes from all over the world, we saw a variety of slabs and enjoyed seeing them up close where we could discern some of the mineralogy.

We transitioned from inside the plant to outside the plant where we were given permission to take as many scrap pieces as we wanted. Some of the material is natural and some is manufactured. We learned quickly how to distinguish which was which as we perused the scraps. Members collected oval and round pieces cut from slabs to make holes for sinks. Smaller round pieces that were cut out for faucets and sink handles will be great for grab bags. Members collected many other pieces for use in grab bags too.

Notable amongst the scraps we collected were two similar things – larvikite and labradorite. Although they both display beautiful blue iridescent flashes, their compositions are very different. Larvikite is an igneous rock named for Larvik, Norway where it was first found. The mineral website mindat.org describes it as a “variety of augite syenite or monzonite consisting of rhomb-shaped ternary feldspars (with a distinctive schiller), barkevikite, titanian augite and lepidomelane.” Labradorite is a calcium enriched feldspar mineral and is named for Labrador, Canada where it was first identified. Named for labradorite, the term “labradorescence” is a particular optical effect where one can see iridescent flashes of color from different angles. Both exhibit labradorescence. Larvikite is often used for countertops, so it isn’t unusual to find scraps of it. I didn’t expect to find any labradorite because I never saw any on prior trips and I thought it would be too exotic for use as countertops. Of course, as soon as I said that to everyone else, I found a piece! It was fun comparing it to the larvikite. Side by side it is obvious that they are very different, but both are exquisite.

Members also found pieces with garnets of varying sizes and colors, tourmaline, different colors of granite, as well as denim sodalite, a marketing term for a rock that contains the mineral sodalite plus other minerals. Some of the manufactured stone is so well made it is hard to tell that it is not natural. It is interesting for its variety of colors and composition, including recycled glass, so we collected samples of it too. One piece in particular caught Charles’ eye and he insisted Cameron Clines had to take it home. The back is stamped with a dragon logo and the brand name “Cambria”, but the last three letters of the name were broken off leaving only “Cam”. As Charles explained, how often do you find a rock with your name on it?

After we collected as much as our vehicle axles could bear, we regrouped at the Elberton Granite Museum. Museum volunteers played a wonderful video for us that explained the history of granite mining in Elberton as well as how mining techniques and equipment have changed over time. We also learned a lot just by strolling around the museum examining the excellent displays.

It was a great trip and would not have been possible without the warm and gracious welcome we received from the processing plant personnel. They are working on many improvements to the plant and invited us back next year to see the exciting changes. Museum volunteers were also very nice and answered all of our questions. A heartfelt thank you to all of them, the members who came and made us laugh, and to Charles for arranging this trip!

Lori Carter
On behalf of Charles Carter, Field Trip Chair
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