These unfinished basalt vessels from an Iron Age workshop at Tel Hazor bear the marks of the basalt-carving process. The Iron Age crafts seem to have been luxury items for the elites. Photo: Courtesy Danny Rosenberg.
For hard, granular materials like basalt, the best (at least, the fastest-working) shaping strategy is to
1) Pound or "Peck" the surface to weaken and introduce microfractures
2) Grind or Scrape away the weakened material...
3) Repeat on "high spots" as many times as necessary...