CALAIS – The topic will be granite, and the speakers are rock-solid.

The granite industry in the St. Croix Valley and Washington County will be discussed at a presentation at 7 p.m. Saturday, Aug. 4, in the recreation center at the Calais Methodist Homes. The speakers will be Steven Haynes and Juanita Sprague of Somesville.

The program is sponsored by the St. Croix Historical Society.

Haynes and Sprague have collected granite from more than 300 abandoned quarries in Maine. Haynes operates the Rocky Coast Rock Shop, a custom lapidary on Mount Desert. The one-hour slide show will feature a discussion about local granite quarries and the men who worked them.

Haynes will talk about the origin and history of granite. He also will show maps that pinpoint where the quarries are located in Maine. He also will display specimens of granite taken from the quarries.

Admission to the talk is free.