How a miraculous discovery at Laurion ultimately saved Athens from a brutal Persian conquest

Located in the rocky hills of southern Attica near the town of Thorikos, the mines of Laurion had been used for centuries before the classical age of Athens.

Archaeological evidence shows that the region had been worked as early as the Early Bronze Age, more conservatively dated to around 2500 to 2000 BC, with mining activity continuing through the Mycenaean period.

However, organised use began in earnest during the 6th century BC. The terrain contained rich deposits of silver-bearing lead ore, and the extraction of this silver became one of the central parts of Athenian economic life.

Control over Laurion allowed Athens to mint its famous silver tetradrachms, which featured the owl of Athena and an olive branch, and were widely recognised across the Aegean and eastern Mediterranean. 

By the early 5th century BC, Athens increasingly depended on the wealth generated from Laurion to fund both civic and military projects, especially because the rich seam had been discovered in 483 BC.

The city leased out mining rights to private businessmen who employed labourers, who included a large number of enslaved people, to dig through the narrow shafts in search of ore.

At the peak of production, according to Xenophon, as many as 20,000 enslaved labourers may have worked in Laurion, though this figure was likely an estimate and did not represent a consistent workforce.

The revenues were collected by the state through taxes and fees, which were then used to fund naval dockyards at Piraeus and state payments.

This financial model was one of the main reasons Athens could compete with other powerful Greek city-states during this time of increasing Persian aggression. 

In approximately 483 BC, a rich new seam of silver ore was discovered at Laurion.

This find came at a time when the Athenians were facing a rising threat from Persia, particularly because the first invasion attempt by King Darius had failed at the Battle of Marathon in 490 BC.

When news of the new vein reached the Athenian Assembly, a debate broke out over how the windfall should be used.

Many citizens wanted to divide the silver among the population, which would have resulted in small individual payments.

However, Themistocles, a well-known politician and strategist, argued forcefully for a different plan. 

Themistocles convinced the Assembly to invest the funds in building a fleet of 200 triremes, fast and powerful warships suited for ramming enemy vessels.

He explained this decision by warning that Athens would soon face renewed Persian attacks, led this time by Xerxes I.

He also clashed with Aristides the Just, who opposed the naval plan and preferred to distribute the silver as dividends.

Themistocles ultimately prevailed, and Aristides was ostracised in 482 BC. The silver from Laurion made this naval expansion possible.

When Xerxes launched his invasion in 480 BC, it was this very fleet that fought at Salamis.

The Athenian triremes, each manned by 170 rowers arranged in three tiers: thranites, zygites, and thalamites, formed the main force of the Greek naval force.

Their victory in the straits near Salamis proved critical in turning the tide of the war.

Without the Laurion silver, Athens would not have had the ships to confront the Persian navy. 

The mines of Laurion were no miraculous gift without cost. The silver was extracted under brutal conditions, primarily by enslaved labourers, many of whom were captured in war or bought from traders.

These individuals worked underground in cramped tunnels only a metre high, as they used picks and chisels to hack through rock by torchlight.

The air was dangerous to breathe due to poor ventilation and the presence of poisonous gases, and the confined work led to frequent physical injury.

Children were sometimes used to crawl into the tightest passages where adults were too large to enter. 

The ore was brought to the surface and refined through a process of crushing, washing, and smelting.

The separation of silver from lead and other minerals took place in large metallurgical workshops, known as ergasteria, where wind and heat were controlled with bellows to drive the smelting fires.

Ancient authors such as Xenophon later described the economic potential of these operations in his work Poroi.

These refining areas left behind large heaps of slag, some of which survive to this day.

Although the mines provided great wealth to the Athenian state, they depended on human suffering.

The mines of Laurion remained active throughout much of the 5th and 4th centuries BC, but several factors contributed to their eventual abandonment.

One major reason was overexploitation. The richest veins of silver became increasingly difficult to find and extract, and the remaining ore was often deeper underground or of lower quality.

As financial risk increased and ore quality declined, many private investors abandoned their operations, and the state struggled to keep the leases viable.

This economic decline was gradual, but it weakened the military value of the mines over time. 

Another factor was war. During the Peloponnesian War, the Spartan occupation of parts of Attica disrupted access to the mines.

After the rise of Macedon under Philip II and Alexander the Great, Athens lost much of its former independence and ability to control regional resources.

Mining activity at Laurion continued sporadically into the Hellenistic and Roman periods.

The Romans, including emperors like Hadrian, attempted to revive mining at Laurion, and later methods allowed the reprocessing of older slag heaps by applying more efficient techniques.

However, production never again reached the levels of productivity or political importance it had in the early 5th century BC.

The mines, once the lifeline of Athenian power, slowly fell silent.