Athens leased its silver mines to private operators

Athens held rights to the silver-bearing deposits at Laurion in Attica, a resource valuable enough to matter directly to the city's finances and military capacity, but actually extracting silver ore required capital for shafts and equipment, skilled labor, and ongoing operational risk that the Athenian state itself had no apparatus to manage directly.

What Athens needed was a way to capture the value of the resource without taking on the operational burden of extracting it — a structure that kept the underlying asset in public hands, so the value didn't simply transfer to whoever happened to have capital, while letting people who did have mining expertise take on the actual work and risk.

Auctioned time-limited leases to private operators, keeping the deposit and taking a fixed share—so the state gained revenue without building mining capability.

Leasing transferred operational risk to private operators with expertise.

Retaining ownership kept the asset public and prevented permanent transfer.

Fixed share gave Athens revenue without needing mining administration.

Operators' profit incentive drove efficient extraction, increasing output.

Separate ownership from operation: lease rights to those with capability, keep a share, and avoid building what you don't need.

That fleet, supported by the roughly 20,000 slaves who worked the Laurion mines and crewed in the battle by free Athenians rowing the ships themselves, went on to win the decisive naval Battle of Salamis against the Persian invasion in 480 BCE, a victory credited with saving Athens and, by extension, the broader Greek resistance to Persian conquest.