geofact


ge·o·fact

G5097750 (jē′ō-făkt′)n. A natural rock fragment having the appearance of an artifact made by humans.
[From geo-, on the model of artifact.]

geofact

(ˈdʒiːəʊˌfækt) n (Geological Science) geology a rock shaped by natural forces, as opposed to a man-made artefact