Ground, smoothed, and traded across whole continents in the Neolithic.
The Neolithic polished axe is flaked to shape then ground and polished to a smooth, often lens-shaped section with a keen edge. Materials range from flint (polished flint axes with mirror facets) to fine igneous rocks quarried at famous 'axe factory' sources and traded astonishing distances.
Check for polish surviving in patches even on damaged pieces, symmetry of section, and the ground edge bevel. Later reuse is common — axes became hammerstones, hones, and even doorstops. Perforated axe-hammers and battle-axes (with a drilled shaft hole) are related but distinct later forms.
Stone sourcing can trace an axe to a specific quarry, so material description matters: colour, grain, any visible crystals. Measure length, edge width, and section, and photograph the polish in low light. These were treasured objects — treat a damaged one as a biography, not a failure.