A modern plaque fixed to the stone identifies it as a mass rock, marking it out as a site where Catholic worship once took place out in the open, away from any sanctioned building or official gaze.

Mass rocks are a particular feature of the Irish penal era, the period roughly spanning the late seventeenth and eighteenth centuries when laws restricting Catholic worship made the celebration of Mass a clandestine affair. Priests officiated at flat stones in fields, on hillsides, and along quiet roadsides, with lookouts posted to warn of approaching authorities. The congregation gathered in the open, exposed to both the weather and the risk of discovery. What makes the Dungannon example quietly interesting is the rock itself, a natural outcrop that happens to carry the form of an altar rather than a dressed or purpose-built stone. The plaque added in more recent times acknowledges that history directly, anchoring an otherwise unremarkable piece of local geology to a specific and serious past use.