GENERAL MEMBERSHIP MEETING

Date: June 1, 2026
Social Time: 7:00 pm
Meeting Time: 7:30 pm
Location: In-Person at GMS and Virtual via Zoom (link is on the GMS calendar here)
Speaker: Aaron Leatherwood
Topic: New location for rare Kyanite twins (Tallulah Falls Formation)

[After] another awesome Mother's Day Gem and Mineral show, we take a breather and focus on our hobby - with field trips, lapidary classes at Wiliam Holland and Wildacres, and everything earth related. Speaking of field trips, we have a very special speaker for June's general meeting - GMS's own Aaron Leatherwood, who will discuss his Geology master's project which started with a find on a GMS field trip.

Kyanite Twinning from unique Georgia location and characterization of twin morphology

Twinned Kyanite crystals were found in regolith formed from schist in the Tallulah Falls formation (near Clarksville). The kyanite formed tabular crystals with visible twins.

Electron backscatter diffraction (EBSD) data was used to confirm the twinning and identify the twin forms. Minerals in the regolith (loose soils weathered from the schist) included kyanite [Al2(SiO4)O] and two kyanite polymorphs (sillimanite and andalusite); as well as two forms of muscovite. Kyanite twins were identified as the common kyanite lamellar twinning (001), but also rare growth twinning along the (100) and (010) planes.

The rarity of the growth twins is due to hyperlocal ionic concentrations in the mineral growth solution during metamorphism, thus growth twins are likely uncommon in the formation. Growth twinning in kyanite was previously reported in only two localities worldwide, Pizzo Forno, Switzerland, and Loliondo, Tanzania.

Bio - Aaron Leatherwood is a Spring 2026 graduate of Georgia State University (M.S. Geology). His thesis was on twinning relationship within kyanite, which started with a find in a GMS field trip. As a student he won the MSA undergraduate award, along with several others from the university and GMS. Aaron’s passion for geology started in middle school, and continues to this day as a Tellus volunteer and GMS field trip leader. He will start his professional life as a field geologist with Atlantic Coast Consulting this month.

Sue Gorday
Vice President of Programs

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General meetings are usually on the first Monday of the month. If this date falls on a holiday, the general meeting will be on the SECOND Monday of the month. In September, the annual picnic and auction replaces the general meeting and is held on a Saturday.