Clay mining soon took over from tin and copper mining as the principal industry in the area, and this eventually contributed enormously to the growth of the town. The clay industry really only came into its own during the mid 19th to early 20th century, at a time when the falling prices of tin and other metals forced many mines to close down or convert to clay mining. The success and high profitability of the industry attracted many families whose breadwinner had been put out of work by the depression in the local metal mining industry, and increased the population of the town considerably. This meant that more shops and businesses took root, providing more jobs and improving trade. This, along with other factors, led to St Austell becoming one of the ten most important commercial centres of Cornwall.