It was found to be an extensive mine, wrought by a set of people at least as expert in the business as the present generation. Some remains of the tools, and even of the baskets used in the works, were discovered, but in such a decayed state, that on being touched, they immediately crumbled to pieces. From the remains that were found, there is reason to believe that the people who wrought these colleries anciently, were acquainted with the use of iron, some small pieces of which were found; it appeared as if some of their instruments had been thinly shod with that metal.
This colliery must have been worked at a very remote period -- at all events, more than one thousand years since, and this argues for the civilization of the inhabitants of Ireland at a period long antecedent to that at which it is generally considered the arts and sciences were first introduced here (From the Irish Fireside, 1883).
Another smaller account is given in the The Industrial Resources of Ireland printed in 1845:
It appears to have been the oldest worked colliery in Ireland, perhaps in the [British] empire, as during the year 1770 the miners broke into an old gallery, the walls of which were lined with stalactites, evidently of great age, and antique mining tools were found therein. The residents of the district had never heard of a tradition of the mine having been anciently worked, and the excavation must have been made at a very remote period indeed.
Unfortunately, there was no tradition of archaeology in Ireland at the time, so this invaluable discovery never made it into the archaeological literature (or museums). While we know the ancient Irish were expert metalworkers, the discovery of the mine in 1770 suggests they were also experts at coal mining. Pit coal would have allowed them to work with much higher temperatures than with charcoal.
This area of Antrim also had a history of salt production since at least the 16th century :
In 1669 the Hearth Money Rolls state: ‘Neare unto this point are two salt pans where salt is artificially made by the boyling of salt water with pit coale which coal pits are very near to the pans aforesaid and yield great profit to the possessour….’.
With six tonnes of fuel needed to produce one ton of salt through the evaporation method, the need for convenient and plentiful energy was paramount.
There was of course no better energy source than coal. It's very possible that coal was used in ancient times in the production of salt. One has to wonder whether somebody during this period noticed the power of the steam that could be generated from coal and whether any attempt was made to harness this power. Perhaps, they thought of an easier way to move those large rocks.....
