Under a Metal Sky by Philip Marsden review – our dark materials

One summer, a couple of millennia ago, the 14-year-old high priest of a meteor-worshiping cult in Syria learned that his cousin, Emperor Caracalla of Rome, had died and that he was to be installed in his place. The teenage priest – later known as Emperor Elagabalus – brought his cult’s sacred stone with him to the capital, where he gave it a goddess for a bride, built it an enormous temple on the Palatine Hill, and ordered Romans to worship it above all other deities. His rule was brief. After four wild years, he was beheaded by his own soldiers and his body was dumped in a sewer. As for the stone, its final resting place is unknown.

Rocks, minerals, metals – these materials from the depths of the Earth and from distant space – have inspired reverence and horror, wonder and greed. They have power over us, and they give us power. It’s likely that the first murderer used a rock. So did the first artist. Our connection with the mineral world is bone deep.

In Under a Metal Sky, travel writer Philip Marsden follows the seam of this story from the defunct tin mines around his Cornish home to the untapped gold deposits of Svaneti, high in the Caucasus. How, he asks, have the materials we shape, shaped us? And what lies behind our often impractical desire to dig, chisel, smelt and collect?

For Marsden, it all started with gravel. He tells of a boyhood spent on his parents’ driveway sifting for shiny nuggets. And later, with hammer and chisel in hand, collecting “muddy lumps of rock which when broken open revealed sparking geodes … quartz in a dozen shades, tourmaline, jasper, gypsum, agates, gleaming galena … Their presence in my room, where I endlessly inspected them, left me with an enduring sense which only later was I able to articulate – that another world lay hidden inside this one.”

For our species, Marsden argues, it began with ochre, a ferrous rock that, if ground and mixed into a paste, can be painted on to almost any surface – art’s foundation stone. “Some cosmic shift took place in that action,” he writes. “Change had always been external, day and night, weather and seasons, rivers and tides, life and death. Now with the use of its own material, the Earth could be subtly remade and modified and abstractions created. Dirt was made precious, stones did tricks, rock became transcendent.”

Travelling east through Europe, Marsden lays bare the Earth’s revelations, from silver to radium, aerolite, mercury, copper, gold and lithium, showing how each has had an alchemical effect on us. He is an intrepid guide: abseiling off cliffs and down abandoned mines, kayaking across the Netherlands, rattling through Georgia in a clapped out marshrutka. He rummages through Goethe’s mineral collection and licks the white fluff growing from the wall of a Slovenian mercury mine. His enthusiasm for the subject is contagious, and he writes with a rock-collector’s eye for glittering details. One senses this is a book he has been longing to write for years.

Are the Earth’s resources gifts or loans? Are they even ours for the taking at all? In earlier times, there was some evidence of reciprocity: the human sacrifices sunk in peat bogs; the deliberately broken and buried swords and spears of the bronze age. A healthy vein of guilt ran through ancient Iranian, Egyptian and Greek beliefs about metals – that they are the flesh of the gods, and to extract them is to tear the divine body. But such ideas were short-lived, and Under a Metal Sky is littered with the toxic tailings of uninhibited greed.

Today’s emperors look once more to rocks from space but, as Marsden observes, their gaze is far from reverent. The internet billionaire Naveen Jain has one of the largest collections of meteorites in the world. “Every single thing we value on Earth,” he has said, “is in abundance in space.” His company, Moon Express, has acquired lunar exploration rights. Why not dig up the moon? Or hoick an asteroid out of the sky? Right now, there’s one floating somewhere between Mars and Jupiter that, if it fell to Earth, would deliver enough precious metals to make everyone on the planet a billionaire. The only problem? We’d all be dead.