The slab is mica schist, a metamorphic rock with a faintly glittering, layered surface, and cut into it is a single incised line forming a Latin cross. No elaborate knotwork, no inscription, no figural carving. Just the cross, pressed into the stone with a single groove, and dimensions modest enough to overlook entirely: 53 centimetres high, 63 wide, and only 6 centimetres thick.

The site sits within the Glendalough monastic complex in County Wicklow, known historically as Sevenchurches, a name that reflects the number of ecclesiastical structures once gathered in this valley. St Mary's Church, immediately to whose north this slab lies, is one of the earlier buildings in the complex. The cross-slab was documented by Patrick Healy in an unpublished Office of Public Works survey from 1972, which recorded and drew the monument as part of a wider effort to catalogue ancient remains at Glendalough. Cross-slabs of this type, essentially flat stones marked with an incised cross rather than carved in relief, are among the simpler early Christian grave or boundary markers found across Ireland, and their plainness tends to place them among the oldest examples of the form. Whether this particular slab marked a grave, defined a sacred boundary, or served some other purpose is not recorded.