Rocks of ages: the world's most memorable stones

Stones have shaped culture for as long as culture has existed. Their uncanny shape has led us to tell stories - of trolls disguised as boulders, of maidens cursed for dancing on the sabbath, of a snake-haired woman whose eyes petrified. They have provided us with tools, from axe heads to the rare minerals used in camera phones. And they have served as signifiers of power and wealth, often derived in turn from mines and the trade routes that distribute their riches. We think of stone as something stable and unmoving, but that's just a matter of the timescale by…