In the 1770s and 1780s the discovery of copper at Parys Mountain in Anglesey which could be cheaply extracted by opencast mining led to a crash in the copper price, and expensive deep mining began to become unviable. As the copper boom came to an end, the mines began to close. In 1788 mining ceased at Dolcoath itself, although some bal maidens continued to be employed picking through the large quantities of ore which had already been brought to the surface.