A History of GlendaloughLast Updated: 22nd Jul 2008
By Stephen Callaghan
A history of Glendalough
When people think of Glendalough, they think of the lower and upper lakes, the monastic site with the round tower. Not too many people know about or even appreciate the important mining heritage which spanned over 150 years in the Valley. It is such a pity that the mining heritage of Glendalough is so over looked.
The first veins of lead ore where discovered in Glendasan valley, just shortly after 1798, by Thomas Weaver who was the mine manger of the Avoca mining operation. Mining of the ore began in about 1800 with a small trial mine.
In 1825 the Mining Company of Ireland bought the majority shares of the mines off Weaver. The price of lead was always a major factor in the viability of the mines. Anytime there was a boom, the MCI could afford to invest in new buildings and machinery. For example, there was a boom in the price of lead in the 1850’s which allowed for a new crusher to be build. When the price of lead (and hence wages) dropped, miners would often leave the area and look for work in England, Australia and North America. The lead was never processed in Glendalough, it was sent 30 miles (as the crow files) to Ballycorus where there was a smelter.
With the increased activity in the area, the population grew. In the 1820’s the population was about 950; this went up to about 1200 in the 1830’s. The MCI built houses for the miners, these houses can be still seen today.
In the 1850’s there was exploration done in Glendalough and more lead veins where discovered further up the valley. These mines where given the name Van Diemen’s Land (because they where so remote). To move the ore from Van Diemen's land to the bottom of the valley, to be crushed a tram way was built, ore filled carts would be send down an inclined track, pulling up an empty cart using a pulley system.
With the continuing development of the mines, the MCI planted 150000 trees in 1857, the timber to be used for mine shaft props.
In the 1880’s the mining started to decline due to the lead ore running out. In 1888 the MCI put the mines up for sale. The mines where bought by the Wynne family in 1890. The Wynne’s had previous mining experience with the mines in Avoca and Glenmalure. Their mining operations in the valley where unsuccessful due to flooding in the mines and a lack of machinery, and their funds eventually ran out.
The Wynne’s set up a water treatment plant in 1913 to treat the waste from Glendalough mine, Glendasan mines and Van Diemen’s Land.
During the first world war the Glendalough mines where brought to the attention of the Ministry of Munitions in London which granted funds for the Wynnes to re-open some of the mines in Glendasan. After the war the funds for the mines dried up, and so did the mining.
In 1948 the mines opened once again by a company called St. Kevin’s Lead and Zinc Mine which was set up by J. B. Wynne. A force of 80 men worked the mines for 9 years. A new crusher powered by an engine was installed in the main valley, its rusting remains can be still seen today. In 1956 a Canadian mining company took over the mines, but this didn’t last long as the mines finally closed in 1957 with the death of a miner and drop in price for lead.
The Glendalough area is mostly composed of granite, this granite body is known as Leinster Granite, which takes up an area of 1500 squared km. The granite formed when magma was trying to reach the surface but cooled on the way. The granite cracked while cooling, this left space for minerals to be precipitated in by hydrothermal fluids. It is estimated that the Leinster granite formed at a depth of 35km and temperature of 650 degrees Celsius.
The mineral veins are hosted in fractures and faults in the granite and compose of galena, sphalerite, pyrite, minor chalcopyrite and quartz, and calcite gangue. They show evidence of brecciation and hydrothermal alteration of the granite host rock.
Today, very few examples of good crystalline minerals can be found. Most of the minerals in the tips are very weathered. Example of crystalline minerals (such as galena) can be found covered in calcite from secondary mineralisation in the veins, but these are scarce.
McArdle, Peadar (2007) “Geological setting of the Lead-bearing veins in the Glendalough-Glendasan district, County Wicklow”, Journal of the Mining Heritage Trust of Ireland, No. 7, p.3-7.
Cowman, Des (2007) “The Mining Company of Ireland’s operations at Glendasan-Glendalough 1825-1895”, Journal of the Mining Heritage Trust of Ireland, No. 7, p.45-49.
Warington, W. Smyth, M.A., Camb (1853) “Records of the School of the Mines and of Science Applied to the Arts” Vol I, Part III On the Mines of Wicklow and Wexford
Moreton, S. & Green, D.I. (2007) “The mineralogy of the Wicklow lead mines”, Journal of the Mining Heritage Trust of Ireland, No. 7, p.19-32.
By Stephen Callaghan
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