The copper mines prospered for about seventy years, but by the early 17th century the industry was in decline. Demand for copper fell and the cost of extracting it was high. Graphite mining continued, and quarrying for slate began to grow in importance. Other small-scale industries grew up, such as tannery and weaving. Although the boom of the mid-16th century had finished, the town's economy did not slide into ruin, and the population remained generally constant at a little under 1,000.