The stone axe was the primary and essential tool for farming, carefully made in a variety of styles, and often polished. The products of axe factories next to sources of porcellanite, an especially good stone, were traded across Ireland; the main ones were Tievebulliagh and Rathlin Island, both in County Antrim. There were also imports from Britain, including products of the Langdale axe industry of the English Lake District.