Kerbourg menhir, Prehistoric menhir in Saint-Lyphard, France.

The Kerbourg menhir, also called Pierre Blanche de Kerbourg, is a 2.10 m block of white quartz standing upright in a field at Saint-Lyphard, Loire-Atlantique. The stone is roughly rectangular, wider at the base and tapering to a rounded top, its pale surface mottled with grey, green and brown lichen and split by deep vertical cracks. A hollowed, shadowed section sits near the top left, and low green foliage hides part of the base.

The menhir was excavated in October 1896 by Henri Quilgars. He noted that the ground around it was full of Gallo-Roman tile fragments (tegulae), and that the stone's base was itself wedged with this material, suggesting it was erected or re-erected in the Roman period. Until the early 20th century a granite slab known as Tombé-du-Loin stood nearby; Quilgars judged the two megaliths independent and dated the slab to the Neolithic, the white stone to Roman times.

The stone is also called Pierre Blanche de Kerbourg or Pierre de Trémélu, and Pitre de Lisle recorded it together with a second slab, the Tombé-du-Loin, as the menhirs de la Pierre-Blanche. Henri Quilgars, who excavated here in October 1896, judged the two megaliths independent and dated to different periods.

The stone stands in open ground at Kerbourg, in the commune of Saint-Lyphard, Loire-Atlantique; the ground around its base is partly covered by low vegetation, so watch your footing near the stone. No facilities are recorded at the site, and the sources describe no marked trail or information panels. The stone is 2.10 m high, so it can be examined on foot from close range.

The cup marks Henri Quilgars recorded in 1896 were not on the standing stone but on a granite slab called Tombé-du-Loin, then still lying nearby. He distinguished hemispherical hollows about 3 cm across, possibly abraded with stone, from conical ones cut with a metal tool. Flint flakes lay beneath the slab.