Apparently this is a 1m tall wedge, 60cm at its back end, 10cm at the narrow end of the wedge. Aligned NW/SE, pointy end to the SE. Top surface with much weather induced pitting.
An entry from Ancient Stones, an online database that covers most of the standing stones, stone circles and other stones found in South East Scotland. Each entry includes details, directions, photograph, folklore, parking and field notes on each location.