The Evans family had, for the last two generations, controlled the leases that allowed virtually sole-control of coal mining rights in Neath.
Earlier, in 1690, rich mineral deposits had been discovered in the Gogerddan estate, whose lease was controlled by Sir Carbery Pryce, whose company developed the site.
With the dissolution of the Society of Mines Royal, also in 1690, this estate became very important, and Mackworth acquired Pryce's interest after his death in 1694.
This led Mackworth to begin smelting copper at Melincryddan in Neath, but found himself in direct competition with Sir Edward Mansel, who owned coal mining in the neighbouring areas.
Mackworth employed the use of wooden waggonways to transport coal from his mines on the Gnoll estate to the wharf at Neath and to supply his copperworks at Melincryddan.
In 1699, Mackworth was among a group of layman who helped Dr. Thomas Bray in the formation of the Society for Promoting Christian Knowledge, an Anglican mission organisation.