Science Spin November 2009

Shankill's abandoned lead mine

By Tom Kennedy

One of the most prominent landmarks in south County Dublin is the tower like chimney that tops the hill at Ballycorus, the 80-foot-high chimney is a striking structure of granite, and it is high up and exposed to the winds for a very good reason. Its function was to carry away the noxious fumes generated by the lead works lower down to the west. A tunnel like flue runs back down the hill for about a mile, an amazing construction, and apparently the envy of smelters through the United Kingdom.

IMPRESSIVE

In the early 19th century, Robert Kane, writing in his Industrial Resources of Ireland, described it as one of the best of its kind, and even now the chimney and flue make quite an impression. Most of the great granite steps, set into the outside of the chimney and spiralling upwards remain, and at one stage several courses of brick added to the already impressive height.

Less visible, but more impressive in some ways, is the long tunnel, snaking its way through the undergrowth down to the old works. Long sections of this are still intact, and where the roof has collapsed, perfectly constructed archwork is exposed. Building the flue and chimney was a massive investment, and one of the ways the mining company got a return from this was to periodically scrape sulphate of lead deposits off the inner walls.

Fluctuating prices for lead sometimes made it harder to make a profit, but the company seems to have had a more enlightened approach to cost control than many other industries of that time, for as Kane wrote, workmen with barrows were only allowed enter the flue after it was thoroughly ventilated.

The former works is still occupied, but not as a smelter. After more than a century of operations, the Mining Company of Ireland moved out in the 1920s, but the high shot tower remains as a reminder of how extraction and refining of lead and silver was an important part of the regional economy. Originally, lead ore for the works came from a mine shaft running west from the chimney, and this is the area now strewn with blankets of spoil. Picking through the spoil can be a rewarding experience, for every so often a heavier lump of ore, in the form of grey coloured galena, lead sulphide, turns up. Cerussite, lead carbonate, also occurs.

The minerals occur at the junction of Wicklow granite with the much older surrounding rocks, and they were were carried up from the depths to fill cracks and crevices by enormous heat and pressure.

BEGINNING

Mining began there in 1805, and if we follow the same geological junction we find old lead mines to the east by the coast, and going south west inland by Glendasan Valley, Glendalough, and Glenmalure. Early prospectors obviously followed that trail, but not always with success. At the north end of Killiney beach, half-hidden around an outcrop, where the granite of Dalkey Hill meets the Ordovician mica-schists, is the cave-like entrance to an old mine, predating Ballycorus by half a century, and reported to have been worked for lead and copper.

This mine probably never turned in a profit so it was abandoned, while Ballycorus remained sporadically productive, hitting a high in the 1840s when a silver rich vein was discovered. Even so, the original mine at Ballycorus never produced enough to keep the adjacent smelting works in full production, and as yields there decreased, the company carted in supplies of dressed ore from the much more productive mines in Wicklow and Caim in County Wexford.

The shot tower erected in 1829, was described by Kane as "a handsome construction" with a spiral stairs within terminating in an "artistic iron verandah" on the outside. The tower was essential for production, for a great deal of the lead produced in the 19th century went into producing rounded pellets of shot, for then, as now, there was no shortage of guns. The shot was produced by dropping molten lead through a grid, and given enough distance, the balls of metal were solid before they reached the bottom.

WORKS

At the works, the ore was smelted, and the lead cast into ingots. Silver was separated out by a process that involved repeated heating and cooling. Lead has a lower melting point, so as the silver rich mix cooled, it solidified first and could be picked out.

According to Walter Freeman, author of Pre-Famine Ireland, developing that silver extraction process added to company profits, and until this could be done, the more valuable ores had to be sent to England or Holland. That difference could mean a lot to a company exposed to fairly sudden fluctuations in pricing and competition from England.

Taxation was a sore subject, hotly debated at public meetings in Dublin. When excise duties on imports of lead were dropped in 1828 the price fell from £30 to just £16 a ton, and Irish producers struggled to survive, yet survive they did. Five years later prices were up, and the Mining Company of Ireland began investing more in the Wicklow mines. By 1836 the company also had control of the Caim mine in Wexford, where 130 men were employed. Caim was once thought of as the most productive mine, producing high quality ore of 75 per cent galena, yet by 1846 the place had been virtually abandoned.

The success rate in Wicklow, at Glendasan and Glendalough, was better and mining continued there for a longer period of time. Strangely enough, the rebellion of 1798 may have played a part, for the discovery of lead ore at the head of Glendalough and Glendasan Valley was made by Thomas Weaver, an engineer working on the construction of the Military Road, a project designed to bring troops up into the valley hot spots of rebellion. Thomas Weaver had also been sent into Wicklow to search for gold, so he had the expertise both to spot the veins of galena and to act on that knowledge.

THRIVING

A company was formed, and mining began at Luganure, on the slopes of Camaderry Mountain in 1809. When the Mining Company of Ireland, owners of the Ballycorus smelter, took over in 1824 Luganure was regarded as the most important mine in Ireland, producing lead and silver in abundance. At the time, 200 men were working below and above ground, and about 120 tons of lead ore were being produced each month. Houses and a school were built for the miners, and the whole area must have been alive and not just with industry. One long line of houses rang out with so much music that it became known as Fiddlers Row.

The same mineral rich junction between the granite and schist continues obliqely across from Glendasan to the upper end of Glendalough, and in 1850 miners were at work there as well.

The mountain was riddled with a network of adits, and by 1859 both sides of the valley had been connected underground, perhaps deliberately because this helped solve some expensive problems connected to drainage of water and access to crushing facilities, which were located on the less productive Glendalough side.

DECLINE

Although the Luganure Mine had always been more important, a massive decline in prices, from €20 a ton in 1887 to just €9 a ton in 1888, sealed its fate. The mine went up for sale and many of the miners emigrated.

In 1890 Albert and Wyndham Wynne bought Luganure, and almost as an aside, Glendalough, not so much for the minerals, as for the grouse shooting. The Wynne family had long been associated with mining in the Wicklow area, but it seems that all they could do with their latest acquisition was to pick through the mountains of spoil to gather ore that has been missed by the original miners.

With the First World War there was a temporary return to work when the British government, concerned about a shortage of metals, stepped in with a £2,500 grant, but as soon as hostilities ceased, so did the support, and once more the miners were out of work.

If nothing else, the Wynne family must have been persistent, for in 1948 St Kevin's mine was opened up again at Glendasan, and for the nine following years 55 out of a workforce of 80 toiled away underground, driving one tunnel, known as Fox Rock, through the mountain for a distance of three quarters of a mile.

Although it was said that there was no great shortage of ore, the mine became less productive, and for one last year, it was leased out to a Canadian company. In 1957, the year in which the mine had one of its rare fatilities when a drill hit dynamite, the mine closed, and this time there was no going back.

The loss of jobs was a big blow to the area, leading one TD, Dr Esmonde into a heated exchange with the then Minister for Industry and Commerce, Sean Lemass. With some persistence, Dr Esmonde kept asking the minister what did he propose doing about the "thirty disemployed". Sean Lemass responded that he knew no more than what he had read in the papers, adding that: "This is a private company operating a private mining right and they are entitled to be protected against the publicising of their affairs."

The miners now had a choice, melt back into the background, or emigrate to apply their skills in Canada or Australia. Many families with mining connections remain in the area, and in a fascinating and valuable project, pupils from St Saviour's NS, Rathdrum, and Scoil Naofa in Glendalough, talked to two former miners who recalled what it was like to leave the crystal clear mountain air and clamber into the gloom to spend hours on end hacking out lumps of rock.

As the old miners explained, the men outside, who worked the crushers, earned less than those inside, and before they could become drillers, they first had to spend time as an assistant. The drills were operated by compressed air, and in a day one driller and his assistant could make thirty, five foot deep, holes. Dynamite inserted into the holes could blast out 15 tons of rock, all of which had to be brought out for crushing and sorting to extract the ore.

It was hard work, but as the miners remarked, the financial rewards for working long hours underground were a lot better than they could ever earn working for the County Council.

Above Glendalough's upper lake the remains of buildings and crushing machines lie abandoned. Higher up the view back over the lakes adds to the atmosphere of isolation, and even when the mines were being worked, they were not that easy to reach. A stiff climb before and after a hard day's work. Going up to one particular mine required such a climb that it became known as "Van Diemen's Land". The mine entrances are now just so many dead holes high up on the valley sides, and streaming down from them is the hard won broken rubble of a discarded industry.

GEOLOGY

Millions of years ago as great earth plates collided, the granite that forms the backbone of Wicklow pushed the older crust up and aside. In doing so, the edges of the older sedimentary rocks were subjected to enough heat and pressure to transform them into schists with their distinctive sheen.

The world was in a turmoil, and super heated mineral rich fluids were forced up into the cracks and crevices between the granite and the schists. Eventually the cooling granite crystalised, and the injected fluids became the minerals that we value so highly now. Most of the minerals that occur along this junction are in the form of galena, sphalerite, and purite, together with an abundance of quartz, and crystaline calcite.

GLENMALURE

Beyond Glendalough is the more isolated Glenmalure Valley, and here too, lead was mined, possibly from before the turn of the eighteenth century. Thomas Weaver, who was responsible for opening up the mines at Glendalough, recorded substantial underground workings, and in 1811 an output of 334 tons of lead was reported. Later, in 1853, the geologist, Warrington Smyth, noted a vein of lead extending for over 3,000 feet.

Even more remote than the upper reaches of Glendalough, working the mines must have been quite a challenge, even for the investors. One of the mines, Baravore, was abandoned in 1853, but undaunted, optimistic investors raised £6,500 in £1 shares to reopen the workings in 1859. Most of this money seems to have gone into the ruins that we see today, and they were hardly finished when the venture collapsed.

Unlike Glendalough, or the mine in Wexford, ore was smelted into lead at Glenmalure. Unfortunately, the evidence for this was obliterated not that long ago when the ruined smelting works was levelled for use as a car park. No doubt many of the people who park there now would have come to explore the industrial heritage.