It's frequently stated that Themistocles persuaded Athens to use revenues from a newly discovered silver mine to finance the construction of a fleet.
The alternative suggestion was to distribute the money to Athenian citizens.
I'm having trouble wrapping my head around this incident, and I think it's more of a human nature and economics question.
A city finds a bunch of metal in the ground, and all of the sudden they can afford to build a navy? How would distributing the silver to everyone in Athens have made everyone wealthier?
Was this only possible because silver was so widely accepted in the "international" world at the time? Did the Athenians require specific commodities (wood, labor) from other cities that were not available within Athens and required foreign trade?
I don't entirely understand the question here. Silver was used to mint coinage, coinage is...well...coinage. Fleets in the ancient world were not just a bunch of boats built from some timber with a gang of schloobs on board to to the rowing. They were highly-engineered, with crews that had to be well-trained and keep themselves in good condition year-round and at a state of constant readiness lest they had to be called up. Large fleets were unimaginably expensive--so expensive that the Romans even as late as the 1st Century, B.C. would only recruit navies as specifically needed for individual campaigns in part because of the incredibly drain it took on resources. The silver vein at Laurium was enormous--during the 5th Century the Athenians could get something like a thousand talents out of it, and at its initial discovery at least a hundred talents were instantly made available. I don't entirely understand what you're asking however, particularly in your last paragraph. Are you asking if they needed the money to afford the raw materials to build the fleet? Or are you asking why silver in particular would be important for the material wealth of the city? Or am I missing something completely?