The meeting line or interface between two pieces of stone; in geology, the term also refers to a natural fracture or fissure in rock.
In stonework, a joint is the place where two stones meet. Joints may be designed to receive mortar, remain extremely fine, or be shaped in specialized ways to protect edges, control alignment, or improve weather resistance.
In geology, joint also refers to a natural fracture or fissure in rock. For sculptors and stone carvers, recognizing natural joints before carving or installation is important because they can influence the strength and behavior of a block.
Etymology
From French joindre, “to join,” ultimately from Latin iungere, “to join or yoke together.”
Sculptor Notes
In monumental sculpture, a joint can be both an engineering necessity and a visual decision. Its placement should respect load, water movement, edge strength, installation sequence, and the continuity of the sculptural form.
References
https://www.pierres-info.fr/glossaire/index.html