Silver mining
Hardrock mines tend to last longer than placer gold mines, and so silver mining towns last longer and have more time to develop than placer gold rush towns, which often peak within a few years. Silver mining towns typically last a few decades, with time to develop the opulence and luxury that only left the slightest traces in placer gold-fevered places such as Dawson City in the Klondike. By contrast, "silver cities" like Aspen, Colorado, and Nelson, British Columbia, often survived as functioning economies into the era of modernization and the advent of tourism (which sometimes proves richer than any silver mine).