| Site Description |
|---|
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: view south-east towards Bog Shaft. |
|
| Highlights: |
|---|
| The Whitespots - Conlig lead mines is an extensive site comprising several spoil heaps, tailings impoundments, capped mine shafts and architectural features including engine houses and chimney stacks. The spoil material contains hydrothermal vein minerals, notably galena, chalcopyrite, barite, dolomite, calcite and rare harmotome (the only known occurrence in Northern Ireland) and ore textures that demonstrate the origin of the mineralization. Museum-quality crystalline specimens of these minerals have been recovered from the site during the past 15 years, and there are many specimens from the site in the Ulster Museum collections. |
| Introduction: |
|---|
| The Whitespots - Conlig site is situated between c.1.5 and 3km north of the town of Newtownards. A comprehensive account of the history of mining in the area is given by Woodrow (1978). The site straddles sheets 29 and 37 of the Geological Survey of Northern Ireland. The memoir that accompanies sheet 29 gives a detailed summary of the geology and mining history (Griffith and Wilson, 1982). Sheet 37 was published in 1986 and the accompanying memoir (Smith et al., 1991) contains an old photograph of the mine area and a brief review of its economic geology. Three photographs taken in the 1940s and descriptions of the site are included in a book by Kirkpatrick (1998?). |
| Extensive working of lead ore took place in this area in the early nineteenth century, when up to 15,000 tons of refined lead (and lesser copper and silver) were extracted from ore removed via several shafts. Production declined after 1854 and the mines had closed by 1900 (Woodrow, 1978). The lead vein (not now exposed) trends N6°W and dips at 75°W (Griffith and Wilson, 1982), and is associated with a 'crush breccia' within Silurian greywackes and shales. During the 19th century the vein was mined over a length of 1.6km and to a depth of 366m, with access through 10 shafts and adits. The trend of the lode is marked by a north-south topographic depression or an east-facing escarpment. |
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: spoil at North Engine Shaft. |
Although the mines are flooded and inaccessible, material is still readily available from spoil heaps adjacent to the two main shafts, namely the North and South Engine Shafts. Much of the mine area has recently (1998) been developed as a country park by the Department of Environment for Northern Ireland.
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: Somme Heritage Centre. |
The most direct access route to the site is from the Somme Heritage Centre car park located close to the Bangor-Newtownards dual carriageway (A2). |
| Description: |
|---|
| The mineralization occurs in silica- and dolomite-cemented breccias and vein-fills. Most of the economic ore material appears to have been in vuggy dolomite-cemented breccias and in barite veins. Sulphides present are galena, chalcopyrite, pyrite, and ferroan sphalerite. The gangue minerals are chalcedony, quartz, dolomite, calcite and barite. Secondary weathering products include cerussite, hydrozincite, bornite, malachite, azurite and limonite. Pyromorphite has been reported but was not observed in this study. |
| The most abundant hydrothermal mineral is dolomite, which varies from yellow-beige to pink to cream in colour and forms sugary to coarsely crystalline aggregates incorporating angular fragments of country rock, and saddle-shaped crystals in vuggy cavities. Barite is also an abundant gangue mineral, forming white, platy aggregates and occasionally well-developed colourless crystals. Calcite is common as a late cavity- or vein-fill, in both silica- and dolomite-matrix breccias. Calcite occurs as flattened rhombohedra, 'nail-head spar', equant crystals with pentagonal faces and barrel-shaped crystals. |
| Galena and chalcopyrite are the principal metallic minerals with minor ferroan sphalerite and pyrite. Galena occurs as crystalline masses within the dolomite-matrix breccia and occasionally as well-formed cubic crystals in vugs. Sphalerite forms dark brown, 2-10mm crystals usually enclosed within barite. Chalcopyrite typically occurs as well-formed 2-8mm crystals perched on saddle dolomite. |
| Of particular interest is the occurrence, in very small amounts, of the barium zeolite mineral harmotome, (Ba,K)1-2(Si,Al)8O16.6H2O. It typically forms transparent, perfectly developed, cruxiform twinned crystals, up to 0.3mm in width and 2mm in length. Harmotome occurs late in the paragenetic sequence and its crystallization is associated with a dolerite dyke of probable Palaeocene (Tertiary) age which intruded through the older breccia and vein mineralization (Moles and Nawaz, 1996). This occurrence of harmotome is the first recorded for this mineral in Northern Ireland. A brief mention by Tschernich (1992, p.242) originates from information supplied by one of us (RN). |
| Importance: |
|---|
| The Whitespots - Conlig mine was one of the largest underground mines in Ireland in its heyday. Many features of the mining activity remain, and specimens of galena and other minerals are readily obtained. The site is the only occurrence in Northern Ireland of the unusual barium zeolite, harmotome (Moles and Nawaz, 1996). Since 1994, the site has been used regularly for field visits by students undertaking project work in connection with the MSc course in Applied Environmental Sciences at Queen’s University Belfast. In May 1997, the Mining Heritage Society of Ireland lead a field visit to the Lead Mines and members of the society urged one of us (NM) to become active in conserving and promoting the site. We feel strongly that action is required to conserve features of the site, which includes buildings in various states of dereliction, and to promote interest in the significance of these features to a wider public. |
| Interpretation: |
|---|
| Griffith and Wilson (1982) considered that initial brecciation and quartz veining occurred during the Caledonian orogeny, followed by re-brecciation and mineralization during the Hercynian orogeny, and finally intrusion of the dyke in the Tertiary. Moles et al. (1997) agreed with this interpretation, and postulated at least four stages of mineral deposition: (1) milky quartz veins similar to barren 'Caledonide' veins which are widespread in the Lower Palaeozoic strata; (2) an epithermal phase characterised by brecciation and silicification of the host rocks and deposition of chalcedony; (3) further brecciation and deposition of Pb-Zn-Cu sulphides with barite and dolomite (mesothermal or MVT-related?); and (4) encrustation of cavities with a low-temperate pyrite-calcite-zeolite assemblage. An episode of fracturing between stages 3 and 4 is indicated by evidence of deformation such as clay-cemented shattered barite. This fracturing may be related to Permo-Triassic faulting in the Newtownards area. |
| From fluid inclusion studies, Moles et al. (1997) concluded that the dolomite, barite and associated 'main phase' sulphides at Whitespots were deposited by hydrothermal fluids similar in chemistry and temperature to those which formed sub-seafloor components of the Irish Carboniferous stratabound ore deposits. Sulphur isotope values from Newtownards sulphides and barite (Parnell, 1995) are similar to values from sulphides and barite in vein-hosted mineralization of presumed Carboniferous age elsewhere in the British Isles. Moles and Nawaz (1996) considered that the intrusion of the Tertiary dyke into the pre-existing mineralized breccia generated localized hydrothermal activity that resulted in the crystallization of pyrite, calcite and harmotome in joints and vuggy cavities. Tschernich (1992) suggests a temperature range of 60-85°C for harmotome crystallization, which accords with this hypothesis. |
| Conclusions: |
|---|
| The Whitespots - Conlig site was designated as an ASSI by the DoE on 25 August 1998. The grounds for designation were largely based on its mineralogical and metallogenic importance, with an additional reference to the unusual diversity of plant species that grow on the spoil heaps and tailings area. |
| Notes: |
|---|
|
| No Notes |
| Access |
|---|
| Management: |
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: 4x4 on tailings area. |
In addition to the nuisance aspect of their activities, the motorbikes and all-terrain vehicles are also contributing to severe erosion of paths, rock outcrops and spoil heaps. Restrictions to the area used by the scramblers, or preferably relocation to another area away from the Lead Mines site, is desirable to allow proper conservation of the site and management of the Country Park.
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: eroded tailings empoundment. |
The eroded, lead-rich tailings impoundment areas south of the Windmill present a health hazard (Moles et al., in prep. 2001). They should be re-vegetated by temporarily fencing-off this area and applying topsoil with grass seed. The spoil heaps beside the South Engine Shaft, Windmill and North Engine Shaft should NOT be topsoiled or vegetated as they do not present a health hazard and must be kept exposed for their geological interest. The availability of useful specimen material should be maintained by periodical (e.g. every two years) relocation of some spoil from both these sites. |
| |
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: North Engine Shaft chimney. |
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: South Engine Shaft chimney stack. |
 | | Whitespots-Conlig Lead Mines, Newtownards, Co.Down, July 1997: Windmill stump and spoil. |
It is recommended that a structural survey be undertaken of the remaining mine buildings, namely the North and South Engine Shaft chimney stacks, Windmill, Bog Shaft Engine House and the Conlig Shaft Engine House. Lightning conductors should be installed and a restoration program should be implemented to ensure no further deterioration of these buildings. |
| | The Lead Mines site deserves its own Interpretive Centre. This is envisaged as both a tourist amenity and a valuable educational resource providing geological and historical information on the former mines by means of interactive and 'hands-on' displays. These displays would be linked with a numbered trail around the site, and information should be presented on other key geological sites in north Down such as Scrabo and Castle Espie. It would be important to make the exhibits relevant to the National Curriculum to attract use from schools throughout Northern Ireland and in SW Scotland. A more ambitious scheme would be to drain the former mines and drive a tunnel from the Interpretive Centre into the old workings, to allow visitor access. This would be a costly project but would add greatly to the interest and attraction of the site. In the shorter term, provision of an exhibit on the lead mines has been discussed with staff at the Somme Heritage Centre. One possibility would be to convert this into a dual-purpose Centre. |
| Uses |
|---|
| Uses: | The Lead Mines site extends north for 1.3km from the Bog Shaft Engine House located in privately held land 1km north of the urban area, to the Conlig Shaft Engine House which is located in the Clandeboye Estate. The spoil heaps at the North Engine House are situated adjacent to one of the fairways of the Clandeboye Golf Club (indeed, errant golf balls are a hazard here). While much of the site is now within the Whitespots Country Park, current site use is dominated by motorbike scramblers who compete with walkers and other site visitors in using tracks and paths through the site. |
| Educ. Level: | School, undergraduate, postgraduate. |