How effective were tools made of iron compared to tools made of stone or wood? An experiment showed that it took 12 minutes to cut down a 20-centimeter diameter tree with a stone axe but only 3 minutes with an iron axe. After repeating the experiment several times, it was found that work was four times faster using the iron axe, compared to the stone axe. The time it took to re-sharpen the blade after use was also much shorter with the iron axe. It is therefore clear that iron was a revolutionary material for all production activities at the time.