This mine was started by Thomas Bonsall in 1785 and worked on and off passing through a series of ownerships until its final closure in 1913. Initially a lead mine, its main economic mineral was zinc with over 5000 tons of blende being produced.
In 1896 it was worked by the partnership of Bainbridge, Boundy, and McIlquhan, in 1898 The New Castell Mines Ltd employed 77 workers.
There was only one shaft sunk, the engine shaft which was sunk to 27 fathoms or 162 feet, making it a rather shallow mine. This can be seen today covered by a steel mesh. There is also an impressive crusher house very noticeable from the main A44 Aberystwyth road.
The adit was reopened a few years ago when the site was cleaned up and is still enterable albeit over the usual rubbish and occasional animal carcass. Its crosscut to the lode where there is a roomy stope with a flooded ladder winze. Going left and climbing over debris from an opencut the debris filled engine shaft is reached, beyond which is a short continuation with a hanging climbing chain.