European Geologist Journal 48
The Mining Heritage and History of the Silvermines area, County Tipperary, Ireland since the 13th century
by Eamonn F. Grennan1 and Colin J. Andrew
Recorded mining commenced in the Silvermines area of County Tipperary, Ireland in the 13th century and continued, intermittently, until 1993. Silvermines is different from all of the other mining areas in Ireland in its longevity and in the variety of metals and minerals which have been produced, including, copper, lead, zinc, silver, sulphur, iron, barytes and pyrites. On a number of occasions, it was the focal point for rebellious activities, some of which still resonate in the area. The paper links the variety of lithological and tectonic settings and rock weathering with the various mining enterprises. The use of the terms heritage and legacy is discussed. It concludes by listing the many activities of the post-closure era, including the legacy issues, some of which are negative and many of which are very positive.
The name Silvermines is unusual in an Irish context, in that it is an English term. The original Irish name for the village/area is Béal Átha an Gabhann, which translates as “the mouth (of the river) of the ford of the blacksmith”, which implies iron mining or workings of some sort (Figure 1).
Figure 1: Location map.
Silvermines is not the oldest base-metal mining area in Ireland, but what is unique is the length of time, over 1,000 years, during which the deposits were worked, albeit intermittently, and the wide variety of the metals and minerals which have been exploited.
The geology of the Silvermines area and regional setting is very well described by Taylor and Andrew (1978), Philcox (1984), Boland et al. (1992) and Andrew (2019) (Figure 2).
Figure 2: Stratigraphy of Silvermines.
Andrew (2019, p. 13) noted that “…as ideas on “Irish-type” Zn-Pb deposits have swung from exhalative to epigenetic to syndiagenetic, Silvermines has been used to support all of these models. More recently detailed isotopic results and tectono-stratigraphic dating have confirmed the exhalative–syndiagenetic models proposed in the 1970’s and debunk replacive models of the 1990’s.”
So, what is an “Irish-type” Zn-Pb deposit? In simple terms, it is a Zn-Pb rich mineral deposit that formed during or soon after lithification (diagenesis) of the host sediment (normally carbonate) and exhibits most or all of the following characteristics:
- Orebodies have single or multiple stacked, typically stratabound, lenses;
- Structurally controlled – adjacent to normal (generally listric) fault complexes;
- Mineralization: Sphalerite, galena, Fe sulphides and barite;
- Gangue: Calcite, dolomite & silica (and haematite);
- Host rocks: Platformal limestones with or without dolomitization.
At Silvermines the Lower Zone Orebodies (Lower G-, K-, C-, P- and C-Devonian as well as Shallee and Gorteenadiha) show classic epigenetic features and are closely structurally controlled. Equally, the Upper Zone Orebodies (B- and Upper G-Zones) show abundant sedimentary features such as syn-sedimentary slump breccias, graded-bedding, interbedding of pyrite and shale layers, and geopetal structures confirming the sedimentary origin of the stratiform pyrite bodies (Figure 3) (Andrew, 2019).
Figure 3: Structure and main orebodies.
Deep Tertiary-aged weathering resulted in the oxidation of sub-cropping sulphides in the P-Zone. This led to the development of significant deposits consisting of smithsonite and hemimorphite. An evaluation in 1933 determined a resource of 0.5Mt @ 21% Zn, modified to 0.85Mt @ 14.3% Zn, 1.7% Pb by Ennex International in the early 1990s. These deposits were exploited intermittently from the 17th century until 1953.
Tertiary karstic weathering is endemic throughout the area, especially in the valley north of the mine and west of the Magcobar Pit and has created a large volume of cavitated ground. This held a substantial volume of acidified water which almost caused the inundation of the mine in the early 1970s, although fortunately no injuries or fatalities were sustained.
Although no written records exist, apocryphal stories in later accounts suggest that silver was exploited in the area by the Danes in the 9th and 10th centuries.
In 1289 Italian miners from Genoa and Florence sponsored by the English Crown came to County Tipperary in search of silver [Gleeson (1937) cited in Cowman (1988)] and opened (re-opened?) a silver mine which they operated until 1303.
In 1631, all the mines in Munster “were let to Messrs Whitmore and Webb”, who concentrated their activities on Silvermines, but “it seems that they found no silver – only lead and copper”. Ownership changed hands regularly. An interesting finding of this compilation is that one of those owners was the first Duke of Abercorn, whose direct descendant – the present Duke of Abercorn – was very active in Irish exploration during the fourth quarter of the 20th century. The mines were finally destroyed in the rebellion of 1641 (Cowman, 1988).
At the end of the Cromwellian era in Ireland in 1653, his soldiers were owed a lot of money and, as was the norm at that time, they were paid by “settlement”, that is, lands were confiscated from the vanquished and divided amongst the military. Most of the soldiers then sold the land on to established English landlords in the general area.
Following a series of court cases in England during the late 17th century, the ownership of the mines passed to the Prittie family and this sequence of ownership is well-reflected in today’s mineral ownership map (Figure 4).
Figure 4: Map of mineral ownership.
The near surface lead and silver appears to have been worked out, but in 1724 copper was discovered and had some success, at least for a while, because in 1758 the mine was in the hands of Martin O’Connor, who had moved to Silvermines after his copper-mining enterprise at Avoca, Co. Wicklow failed, but Silvermines eventually also failed.
Circa 1770, the lead veins at Shallee were discovered and both lead and copper was produced for a couple of years. Sometime in the 1780s, “a wedge of rich ore” was exploited and a smelter was built “which produced sheet lead and shot” (Cowman, 1988). Pure silver was also produced. This was a very turbulent time in Irish history, with the insurrection in 1798 followed by the Act of Union in 1801. In 1800 Henry Sadlier Prittie was created Lord Dunally, whose lineage and estate persists to the present day.
In 1840, a number of tests were carried-out “at Gorteenadiha and Ballygowan for sulphur as well as checking the lead potential”. In 1845 the General Mining Company of Ireland amalgamated all of the workings in the district, and “over the next three decades the mines at Shallee, Gorteenadiha, Garryard and Ballynoe were worked”.
Despite the Great Famine (1845–1849) in Ireland, the workings, producing both lead and copper, maintained profitability. However, in July 1853, a combination of low metal prices, near-surface ore being worked out, the failure to maintain investment, poor management and a number of financial irregularities caused major problems leading to a series of strikes because the miners had not been paid their wages. Notwithstanding this, a “new rich vein of silver-lead was reported from Shallee” and was worked (Figure 5) (Cowman, 1988).
Figure 5: Shallee area.
In 1949, the Silvermines Lead & Zinc Company commenced a project based on the “calamine zone” (P-Zone), with the first stage being the development of a ‘pilot’ Waelz Rotating Kiln to treat 40 tonnes per day to produce zinc oxide. The project was unsuccessful and ended in July 1952 (Figure 6).
Figure 6: Knockanroe and Ballygowan area.
Around this time, the Korean War broke out, during which lead prices rose sharply and mining recommenced at Shallee. Over the next six years to January 1958 there was a series of stop-start efforts at production, which is estimated at 4,677 t of lead and 37,000 ounces of silver from 355,000 tonnes of ore (Andrew, 2019).
In 1958 the Silvermines Lead & Zinc Company carried out some exploration drilling and identified what became the Magcobar barite deposit in the Ballynoe area. In 1959 they agreed to assign operating rights to Dresser Minerals from Houston, Texas. Whilst production peaked at 329,000 tpa, it generally produced between 200,000 and 300,000 tpa. During its final two years, the company mined 190,000 t by underground methods (Figure 7).
Figure 7: Magcobar (Ballynoe) area flooded pit.
4.61 Mt of 85% BaSO4 lump grade barite were sold over the life of the mine to the end of September 1993. To access this ore about 8.5–9 Mt of overburden and waste rock were stripped.
In October 1962 the Canadian International Mogul Mines, who had been active at Avoca, concluded a farm-in agreement with the Silvermines Lead & Zinc Company to explore an 80 km2 area at Silvermines. Drilling commenced in June 1963, and the company was very close to terminating the exploration programme when the first significant stratiform mineralization was intersected in hole G33. By December 1964 10 Mt of ore were defined. They then ceased exploration to concentrate on developing the mine. Operations commenced in 1968 at a throughput of 1M tpa, which it consistently achieved over its lifetime until closure in July 1982, having milled 10.8 Mt @ 7.36% Zn, 2.70% Pb from the Lower G-, Upper G-, B- and K-Zones (Figure 8).
Figure 8: Gorteenadiha & G-Zone (Mogul of Ireland).
The mine was quite profitable in the early years and this led to a decision in 1970 to re-start exploration. Day-to-day control was handed over to the company’s wholly owned exploration arm, of which one of the authors (Eamonn F. Grennan) had just been promoted to Chief Exploration Geologist. Over the next three years the Resource and Reserves were increased to >14 Mt.
Post Mogul Mine Closure
The Mogul tailings pond and, to a lesser extent, the now-flooded Magcobar caused much environmental controversy during the 1980s and 1990s. In 2005, the Government announced the allocation of €10.6M for rehabilitation and as part of the preservation of industrial heritage in the area (Morris, 2011).
After the closure of the Mogul mine in 1982, the company was acquired by Ennex International plc in 1983. Ennex decided to evaluate the potential of the area for new ore at depth and shallow primary oxide/sulphide mineralization and, as described above, had some success.
Revolution and Armed Conflict
The first of many known conflicts at the mine took place in 1303. Fourteen years after the arrival of the Italian miners, they were attacked following the killing of a local man and the works were abandoned.
Middle 17th century
A major Irish Rebellion started in 1641, coincident with the Civil War in Britain, that led to the destruction of the mining operations by the Irish under the leadership of Hugh O’Kennedy, brother of John Mac Dermot O’Kennedy, on whose lands the mine was situated (Boate, 1652).
Oliver Cromwell came to Ireland in late 1649 to put down the rebellion and laid siege to the city of Limerick, 30 km southwest of Silvermines. At that time the main route from Dublin to Limerick passed by Silvermines. Indeed, the road leading to the 1970s Explosives Magazine is still known as “Cromwell’s Road”.
A group from the Irish Republican Army (IRA) took over the mine offices on the evening of July 7 1971. During the incursion, one of its members entered the electrical sub-station and attempted to place explosives close to a transformer but died in the attempt. The occupation was quickly quelled by the authorities.
Miners and Other Workers
In the early 1800s the Dunally Mining Company had the motto, “Employ the people, enrich yourselves”, and despite expressing benevolent intentions towards their employees left them unpaid for over a year!! (De Staffort, 2017).
Moving on 100 years, little seemed to have changed, because Griffith (1951), quoted in de Staffort (2017) in relation to the operation of the Waeltz Plant, commented that, “The lack of trained personnel to operate the plant led to many expensive mistakes in the early days and added still further to the general cost. To obtain raw labour from the surrounding farms and outlying villages and to train them as shift bosses and plant operators and to instil into their minds the need for careful temperature control, the accurate sampling of calamine feed, zinc oxide and slag was heart-breaking”.
However, by 1968, things had changed radically, because de Staffort (2017) comments on the fact that, “The social impact of the Mogul of Ireland mine at Silvermines had a tremendous effect on the area, extending to neighbouring towns and counties. It was a high-paying mine and created a variety of skilled, semi-skilled and unskilled jobs. There had never been an industry with such an immediate effect on the hinterland. Workers were drawn from near and far”.
Heritage and Legacy
Whilst researching and completing this paper, it became apparent that in regard to mining, the difference – at least in the English language – between heritage and legacy has become very profound. In the past both words were invariably intrinsically linked with each other, especially in regard to wills, legacies and inheritance. By using Silvermines as an example, it is hoped to illustrate the ambivalent and negative comments which should be addressed as a matter of urgency by the European Commission and the European Federation of Geologists.
In the past heritage was taken to mean a property that had been inherited, that is, an inheritance, whilst ‘legacy’ was taken to mean money bequeathed to someone in a will. In Ireland archaeological studies include buildings, monuments, settlements and also artefacts, a category which includes gold, bronze and iron-based implements. All of these are part of our heritage. More recently the onus has shifted towards post-1700 buildings, especially their preservation. They include large country houses and historic streetscapes and of course include old mine buildings.
It should be noted that when such a building passes from one generation to the next, it is usually by means of a will or legacy. More recently, however, in regard to the mining industry, the term ‘heritage’ has been used to hinder minerals development in phrases such as ‘this is a heritage building and cannot be removed’ or ‘this area is part of our heritage and cannot be interfered with’. Thus, one can see that the term ‘heritage’ is always used in a positive sense, that is, heritage equals good. On the other hand, when one also hears of legacy issues in a mining area, it is invariably used in a negative sense, that is, legacy equals bad. As an example, we will review the Silvermines area. In the public mind, what are the post-1965 legacy issues?
- The Mogul tailings pond, also known as the Tailings Management Facility (TMF), which has been partially re-vegetated and is no longer a problem.
- The waste-rock slopes at Magcobar, which now are also partially re-vegetated.
- The collapsed areas of old stopes are now surrounded by two metre-high safety fencing and therefore are no longer a danger.
- The Magcobar open pit, which is filled with water, is being examined for other purposes (VAMOS, 2019).
Are there other legacy issues? Yes there are, BUT they are all positive and thus receive very little public acknowledgement. As examples:
- The training of the miners, electricians and fitters at Silvermines enabled them to take their skills to newer mines such as Tara, Lisheen and Galmoy and to overseas.
- Finally, it should be recorded that most of the geologists and geo-technicians who worked at Silvermines continued to live in Ireland and went on to become senior managers elsewhere in the industry in Ireland, and/or became well-known and respected consultants around the world. This was not matched by any of the other professions who worked in the mine.
A last word on geological legacy
The Mogul of Ireland Group, which was an excellent employer, did not however fund many geological or educational projects. This was the background to the very propitious paper by Stuart Taylor and Colin Andrew, both mine geologists with Mogul at that time, who in 1977, against a backdrop of less-than-whole-hearted encouragement, submitted a paper to the Institute of Mining and Metallurgy under the title “Silvermines Orebodies, Co. Tipperary, Ireland”. Indeed, it was in this paper that the term “Irish-type” Zn-Pb deposit was used for the first time in the literature. This paper, published in the Transactions in 1978, was deemed to be of such quality and significance that it was awarded the Silver Medal for that year. This in itself is a combination of history, heritage and legacy.
As more and more emphasis is placed at universities upon so-called productive activities, it is important to maintain other disciplines which may not today be seen as productive, but which in the future will provide valuable data – data that if not recorded now could be lost forever. It will serve to highlight the fact that most of the metals identified in the EC list of critical raw materials have at some time in the past 150 years been produced in Europe and, given the right environment, could be produced again.
We wish to acknowledge the role of former Mogul employee Dom O’Halloran, who supplied a lot of personal and unpublished data; Des Cowman, mining historian, for his detailed research and many articles; and John Clifford for all of his suggestions. Finally, Eamonn F. Grennan wishes to acknowledge the many publications of his co-author (Colin J. Andrew), which made the compilation of this paper so much easier.
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VAMOS (2019). http://vamos-project.eu/ (accessed 24 August 2019)
This article has been published in European Geologist Journal 48 – Geological heritage in Europe. Read here the full issue: