Pennsylvania Earth Sciences Association

The Pennsylvania Earth Sciences Association (PESA) is a Lehigh Valley based group of earth science enthusiasts - people who enjoying hammering rock and digging dirt in the quest for better specimens, individuals who prefer attending rock shows that don't result in hearing loss.

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

General meetings are open to members and guests. Anyone is welcome to bring and display favorite specimens, recently acquired material, or unidentified material about which they would like to receive feedback from other club members.

A short business meeting is followed by a formal lecture on a subject within the earth sciences or lapidary arts. Lecturers include members, fellow collectors, professionals from geoscience industries, and university faculty.


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).

Field trips

In a typical year, PESA organizes or participates in 6 to 12 field trips, mostly collecting excursions to local quarries, outcrops, and mine dumps. The club has, on occasion, also organized bus trips to view museum collections such as the Smithsonian Institution and the Museum of Natural History.


PESA has been organizing mineral and gem shows since 1968 and currently runs two shows per year at Macungie Memorial Park.

For more information


visit us on facebook for information on upcoming events


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