Tudhoe Whinstone Mine

Overview

Tudhoe Whinstone Mine worked the Hett Dyke, a narrow wall of hard quartz-dolerite that runs across the Durham coalfield between the villages of Tudhoe and Hett, a few miles south of Durham. The dyke had first been dug out along its outcrop in a long open trench between the two villages, and by 1882 the remaining stone was being won underground from shafts, one near the Darlington road at Tudhoe and others at Hett. The working appears in the 1888 List of Mines under the Metalliferous Mines Act as 'Tudhoe, Whinstone', owned and managed by William Coates of Spennymoor, and was still being returned in 1890, but no whinstone mine at Tudhoe is listed for south Durham in 1902. Whinstone of this kind went for road metal. Nothing is left above ground beyond the line of the filled trench, and the Tudhoe end of the dyke was later cut through by opencast coal working, since reclaimed.

History

The Hett Dyke was known to geologists early. Adam Sedgwick traced it in the 1820s, on the authority of a Mr Wharton of Oswald House, Durham, from the Magnesian Limestone escarpment at Quarrington Hill west-south-west through Crowtrees, Tursdale, Hett, Tudhoe, Whitworth and Constantine Farm to Bedburn Beck and on to Eggleston Moor. Its outcrop between Tudhoe and Hett was the obvious place to win it, and when J. J. H. Teall examined the dyke in 1882 he found that it 'has formerly been quarried on an extensive scale between the villages of Tudhoe and Hett', leaving a nearly continuous east-west trench that ended at Hett village in a vertical face of rock. By then the surface stone was gone and the dyke was 'worked by means of shafts at Tudhoe, near the Darlington road, and at Hett village'. It was this underground working that put the site into the mines returns rather than among the quarries: the 1888 List of Mines under the Metalliferous Mines Act records 'Tudhoe, Whinstone', situated at Tudhoe, with William Coates of 37 Half Moon Lane, Spennymoor, as both owner and manager, in the same short list as Joseph Proud's Hargill whinstone mine at Crook and the Cleveland Dyke mines of North Yorkshire. The Durham Mining Museum's index of managers adds that Coates was returned as its agent in 1890. The mine does not appear in the 1902 list for south Durham, where the only whinstone mine is Howden at Howden-le-Wear, then in the hands of the Auckland Rural District Council, so the Tudhoe working had stopped, or dropped below the size at which a return was required, at some point in the 1890s. The stone was road metal: whinstone is too hard and too irregularly jointed for building, but broken small it made the best road surfacing available before tarmacadam, and the highway authorities of the period were among the customers and, as at Howden, sometimes the owners of these small dyke workings. Teall's specimen from Tudhoe became the reference material for the dyke: Holmes and Harwood analysed it in 1928 as a quartz-dolerite of Whin Sill type, and their photomicrograph of the Hett Dyke is of the same Tudhoe sample.

Geology

The Hett Dyke is the chief member of the most southerly of the four echelons of Whin Sill-type dykes that cross north-east England. It runs roughly N 74 degrees E across the Durham coalfield from Teesdale to the collieries south-east of Durham, where it dies out before reaching the Permian escarpment; the parallel Ludworth Dyke takes over to the north. It is a quartz-dolerite, allied to the Great Whin Sill and intruded with it in late Carboniferous to early Permian time, after the folding and faulting of the Coal Measures. Teall described the Tudhoe-Hett rock as fine to medium grained, dark or bluish grey, free of the porphyritic felspars that mark the Cleveland Dyke, and dotted with small calcite-filled amygdales that effervesce under acid; Holmes and Harwood's analysis of his Tudhoe specimen found the usual Whin Sill chemistry with a high carbon dioxide content from that calcite. Followed through the collieries and along the line of its trench-like quarries, the dyke is not one continuous sheet but a series of at least five members set slightly en echelon, each beginning a little north of its neighbour to the west. Its thickness varies: about 7 feet at Sunny Brow, twice that at Tudhoe, 10 feet at Hett, where it hades steeply to the north, and 9 feet where it was last met underground; the opencast coal workings at Tudhoe exposed it at about 11 feet. The coal-shales alongside are baked and indurated and the coal is coked for a short distance on either side, which is why colliery plans pick the dyke up so readily. Being a near-vertical wall rather than a bed, it could be quarried only as a trench along its outcrop and thereafter had to be followed down from shafts, which is what made the Tudhoe working a mine in law rather than a quarry.

Workings

Two phases are recorded. The first was open quarrying along the outcrop, which by 1882 had left 'a nearly continuous trench' between the Darlington road at Tudhoe and Hett village, ending at the village in a vertical rock face; the Geological Survey later described the same feature as a line of old quarries marked by a partially filled trench, and the 25-inch Ordnance Survey map of the early twentieth century shows it as a single 'Old Quarry' roughly 800 metres long, running east-north-east from a field beside the Great North Road to the west end of Hett. The second phase was underground: in 1882 the dyke was being worked from a shaft at Tudhoe near the Darlington road and from shafts at Hett village, and the Survey records that at Hett it was 'once worked from six shafts'. Nothing has been found on the depth of these shafts or on how the dyke was stoped below the trench; on a body ten to fourteen feet wide the work can only have been confined to the width of the dyke itself, between walls of baked shale. The 1888 return gives no employment figure. Further east the dyke was also quarried on the south side of the railway near Tursdale, where it is still exposed in the bed of Tursdale Beck, but that working lies beyond the Tudhoe-Hett section and is not the mine listed here.

Closure

The working is in the returns for 1888 and 1890 but not in the 1902 list for south Durham, in which the only whinstone mine is Howden at Howden-le-Wear, so it had closed, or had ceased to be returned as a mine, during the 1890s. No source gives a reason. On a body ten to fourteen feet wide that had already been worked out along its outcrop, underground working from shafts could not have paid for long, but that is inference rather than record.

What remains

There is no known surviving working. The trench between Tudhoe and Hett had been abandoned long before the Ordnance Survey mapped it as an old quarry, and by 1961 the Tudhoe end of the dyke had been cut through by opencast coal working and reclaimed; the Durham magnetic survey of that year could not run a traverse across the reclaimed ground because the top of the dyke had been used as the approach road into the workings. The fields between the A167 and Hett are now farmland. No photograph of the trench or of any shaft site has been found on Geograph, Wikimedia Commons or the exploration forums.

Nothing built. The line of the filled quarry trench, running east-north-east from the A167 to the west end of Hett, is the only surface trace of the whinstone working, and it survives as a field boundary rather than as a visible hollow in any photograph found. The Survey noted the dyke's former six shafts at Hett, but no shaft mound is recorded. The dyke itself can still be seen in the bed of Tursdale Beck east of Hett, outside this working.

Nearby mines

• Littleburn Colliery — 3.5 km NW
• Dean and Chapter Colliery — 4.2 km S
• Thrislington Colliery — 4.4 km SE
• Chilton Colliery — 5.9 km S
• Bearpark Colliery — 7.4 km NW

Straight-line distance, within 15 km. Show on the map.

Recorded claims

Individual factual claims, each attached to the source(s) that support it below. Where sources disagree, both are kept.

• The 1888 List of Mines under the Metalliferous Mines Act returns 'Tudhoe, Whinstone', situated at Tudhoe, with William Coates as manager and William Coates of 37 Half Moon Lane, Spennymoor, as owner. ¹
• The Durham Mining Museum's management index records William Coates as manager of Tudhoe Whinstone in 1888 and as its agent in 1890, so the mine was still being returned in 1890. ²
• Writing in 1882, Teall found the dyke 'formerly quarried on an extensive scale between the villages of Tudhoe and Hett' and then 'worked by means of shafts at Tudhoe, near the Darlington road, and at Hett village', with a nearly continuous east-west trench of old quarrying between the Darlington-road shaft and the village, ending there in a vertical face of rock. ³
• At Hett the dyke was once worked from six shafts; westwards its course is marked by a line of old quarries in a partially filled trench, and it was also quarried south of the railway near Tursdale (NZ 2875 3705), where it is now exposed only in the bed of Tursdale Beck. ⁴
• The 25-inch Ordnance Survey map shows the abandoned trench as a single 'Old Quarry' about 800 metres long, running east-north-east from a field beside the Great North Road to the west end of Hett, with a footpath along it. ⁵
• At Hett the dyke is 10 feet wide and hades to the north at a very high angle; the adjacent coal-shales are baked and indurated, and the rock is a dark grey, fine to medium grained dolerite with small calcite-filled amygdales. ^3,4
• Traced through the collieries and along its trench-like quarries, the Hett Dyke is a series of at least five en echelon members rather than one sheet; it is about 7 feet thick at Sunny Brow, twice that at Tudhoe, and thins eastwards to 9 feet. Teall's Tudhoe specimen analysed as a quartz-dolerite of Whin Sill type. ⁶
• The dyke belongs to the Whin Sill suite of quartz-dolerites and tholeiites, intruded after the folding and faulting of the Coal Measures and before the Permian; it cuts Westphalian rocks but does not reach the Permian escarpment. ^4,7
• By 1961 the Tudhoe section of the dyke had been exposed, at about 11 feet wide, in opencast coal workings since reclaimed; no magnetic traverse could be run there because the top of the dyke had served as the approach road into the workings. ⁷
• No whinstone mine at Tudhoe appears in the 1902 List of Mines under the Metalliferous Mines Act for Durham (South); the only whinstone entry is Howden, at Howden-le-Wear, owned by the Auckland Rural District Council. ⁸

Photographs & further reading

Sources

1. (primary) 1888 List of Mines under the Metalliferous Mines Act: Whinstone Mines — Mines Department, via the Durham Mining Museum
2. (secondary) Colliery Management index, names Co-: William Coates, Tudhoe Whinstone, 1888 and 1890 — Durham Mining Museum
3. (secondary) Teall, J. J. H. (1884). Petrological notes on some North-of-England dykes. Quarterly Journal of the Geological Society, 40, 209-247 (the Hett Dyke, pp. 228-230) — Geological Society of London, via the Internet Archive
4. (primary) Smith, D. B. and Francis, E. A. (1967). Geology of the country between Durham and West Hartlepool (Memoir for Sheet 27), Chapter 4: Intrusive igneous rocks - the Hett Dyke — British Geological Survey
5. (primary) Ordnance Survey 25-inch County Series, Durham: the 'Old Quarry' trench between the Great North Road and Hett (georeferenced layer) — National Library of Scotland
6. (secondary) Holmes, A. and Harwood, H. F. (1928). The age and composition of the Whin Sill and the related dikes of the north of England. Mineralogical Magazine, 21, 493-542 — Mineralogical Society, via the RRUFF document library
7. (secondary) Stacey, R. A. (1961). The interpretation of a magnetic survey over the whin dykes. MSc thesis, Durham University (the Hett Dyke, pp. 35-38) — Durham E-Theses
8. (primary) 1902 List of Mines under the Metalliferous Mines Act: Durham (South) — Durham Mining Museum

Record created: 4 September 2026 · Last researched: 8 September 2026