The Planet in a Pebble, By Jan Zalasiewicz

Blake's "world in a grain of sand" was "out by only an order or magnitude or so," writes Zalasiewicz, a seer of geology.

The average 50g pebble contains mostly oxygen, silicon and aluminium, but there will even be "a million billion atoms of iridium", rarest of elements in the earth's crust.

This imaginative scrutiny of this rocky microcosm ranges from the planet Theia, which possibly crashed into the Earth to create the Moon, via the more homely influences of time and tide to the pebble's possible rebirth with "the mineral diaspora from our Sun's final outburst".