Pennsylvania Earth Sciences Association
The Pennsylvania Earth Sciences Association (PESA) is a Lehigh Valley based group of earth science enthusiasts. Our membership is diverse, ranging in age from school-age children to retirees, and in experience level from beginners to advanced. While the majority of our members are interested in mineralogy, their interests extend into related fields of paleontology, gemstones, and the lapidary arts.
PESA was chartered in 1964 to provide opportunities for its members to share information, add to their collections, and learn about other facets of the earth sciences and lapidary arts.
We are incorporated under the laws of Pennsylvania, and registered as a non-profit organization under section 501(c)(3) of the Internal Revenue Code.
Our activities
General meetings
Our meetings are held the third Monday of each month at Helfrich Springs Grist Mill, located at the intersection of Mickley Road and Lenhert Road in Whitehall Township, Lehigh County (less than a mile southwest of Lehigh Valley Mall). Doors open at 6:30 PM.
A typical meeting consists of a short business meeting, followed by a workshop or formal lecture on a subject within the earth sciences or lapidary arts. Lecturers include members, fellow collectors, professionals from geoscience industries, and university faculty. A sampling of previous meeting subjects:
• Collecting in Michigan's Upper Peninsula [VIDEO]
• Garnets [VIDEO]
• The origin of color in minerals [VIDEO]
• Resources for researching Pennsylvania fossils and minerals [VIDEO]
• A brief history of mine lighting [VIDEO]
• Finding new and long lost mineral and fossil localities [VIDEO]
Meetings are open to members and guests. Everyone is welcome to bring and display recent acquisitions, favorite specimens, or unidentified material about which they would like to receive feedback from other club members.
Field trips
PESA has an active group of field collectors, the club organizing or participating in about 8 to 16 collecting trips per year, including day trips to local quarries, outcrops, and mine dumps, as well as multi-day excursions to locations out-of-state. Recent collecting trips have included:
• New York - Herkimer diamonds (2025)
• New Jersey - fluorescent minerals (2025)
• Connecticut (2025)
• Missouri (2025)
• Bancroft, Ontario - pegmatite minerals (2024)
PESA also arranges for group tours of mineral collections or historical museums, and the club has, in the past, organized bus trips to view more distant collections such as the Smithsonian Institution and the Museum of Natural History. Among the recent museum tours:
• The Arthur Montgomery Mineral Museum at Lafayette College (2025)
• No. 9 Coal Mine & Museum (2025)
• Atlas Cement Company Memorial Museum (2024)
• National Museum of Industrial History (2024)
Field trips are open to members only. Membership dues must be paid in full prior to signing up for a field trip.
Shows and swaps
PESA currently organizes two shows each year at Macungie Memorial Park - the Spring Mineralfest on the first Saturday in June, and the Autumn Mineralfest on the first Saturday in October. These shows are great opportunities for collectors to add to their collections as well as to catch up with fellow collectors.
Additional activities
The club issues a newsletter at least ten times each year to keep members informed of all activities. We also get together for a picnic or banquet in spring or summer, and a Holiday party in December.
Social media
Visit us on facebook for discussion of all things geological, and also information on upcoming events.
The PESA YouTube channel has loads of original content, including several videos of past meeting lectures, as well as educational videos covering a wide range of subjects in mineralogy and paleontology and beyond.
Contact information
Mailing address: PESA, PO Box 147, Bethlehem, PA 18016
e-mail: pesanewsletter@yahoo.com
For more information, send us an email. Or better yet, stop by our next monthly meeting at Helfrich Springs Grist Mill. Visitors are always welcome!
Application for membership
2025 Application