Derbyshire lead has been mined in the limestone areas of the Peak since at least Roman times and possibly before as pieces of melted lead and burnt lead ore have been found in Early Bronze Age barrows.
Geologically a mineral-rich magma intruded the fissures and faults in the limestone and as it cooled it crystallised, filling the voids with deposits of galena (lead sulphide ore) often surrounded by crystals of fluorspar (calcium fluoride) and calcite (calcium carbonate). In some areas barytes (a barium ore) is associated with the lead ore. The lead mineral sought by miners was galena or lead sulphide (PbS) but few veins consisted of more than 10% galena. An average galena content was 5% or less and some veins only held 2%. These lesser quality veins were followed in the hope that they would lead to richer ones.
Mining practices varied depending on how the lead ore had deposited.
Rakes are the major veins which can run for several kilometres and consist of minerals filling near vertical fissures up to 15 m wide though more often 2 or 3m. A few have been mined to a depth of 200m but none have been totally bottomed. Often drainage problems limited the mining to shallow depths. A classic example is Long Rake near Youlgrave.
Mining was by sinking shafts at intervals and levels driven horizontally out from the shaft along the ore vein.
Scrins are smaller rakes where the fissures are filled with minerals but often only 50cm wide. Mine working of scrins generally don’t go to more than 50m.
Flats are mineral deposits lying more or less horizontal and thus parallel to the beds of enclosing limestone. They rarely outcrop so most are found by miners following a rake or scrin outwards from fissure veins.
Pipes are irregular shaped linings or fillings of cavities. Like flats they had little outcrop and were found by miners working outwards from veins.
Finding surface outcrops of galena or its associated minerals were the evidence needed for further exploration the veins were then followed.
By the 17th century, however, most easily accessible surface lead had been mined thus searches for evidence of lead ore other than surface outcrop were made by digging trial pits before deciding if an area was suitable to sink shafts.
Without doubt the Romans worked lead ore in Derbyshire and several crude ingots or pigs of smelted lead have been found.
Three pigs of lead, ranging in weight between 37kg and 78kg, and dating from Roman times were found in Matlock in the eighteenth and nineteenth centuries.
The first was discovered on Matlock Bank in October 1783 and is now in the British Museum. The pig was found close to the remains of an old smelting hearth and was only a few inches below the surface.
The whereabouts of the second pig, which was found on Matlock Moor in 1787 and dated from between 41-54 A.D., is unknown.
The third pig was found in good condition on Saturday 24th March 1894 on Mr. Daniel Hurd’s estate at Portland Grange when a labourer was trenching some moorland to a depth of two feet and struck the pig of lead, which was lying face down, with his spade. It was found probably less than half a mile away from the Wolley pig. At the time of its discovery it was described as the finest pig in existence.
A pig from the same mine was found on nearby Cromford Moor in 1777; it shows the name of the Roman Emperor Hadrian, so can be dated to about 130 A.D. It was preserved by Peter Nightingale of Lea and given to the British Museum in 1797.
The Derbyshire pigs have inscriptions and are distinguished by the letters LVT or LVTVD or in one case LVTVDARES, all are belived to refer to Lutudarum. There are many suggestions as to the location of Lutudarum but as yet no undisputable evidence.
Even though The Romans had the knowledge for deeper mining it is thought they probably opencasted the lead ore from the major vein outcrops. Artefacts associated with lead working have been found at Elton, Crich and Longstone Edge but the records do not state if found at surface level or underground.
After the Romans left mining was thought to have continued on a much smaller scale.
Repton Abbey who owned the mines at Wirksworth sent a leaden coffin to Crowland Abbey in Lincolnshire in 714 AD for the remains of St Guthlac. They were still the mines in the 9th century as in 835 AD lead worth 300 shillings had to be paid to Christ Church, Canterbury.
In 874 the Danish army destroyed Repton Abbey and the Manor of Wirksworth along with its lead mines passed to the Danish King Ceolwulf.
The Domesday Survey of 1086 records lead production at the time of Edward the Confessor for the combined manors of Hope, Ashford and Bakewell who annually rendered 5 cartloads, each of 50 slabs of lead metal, each slab weighing about 40 lbs, as a levy or duty to the Crown.
By 1086 seven plumbariae or lead works are recorded – three at Wirksworth, and one each at Matlock, Ashford, Crich and Bakewell.
By the Middle Ages lead was in high demand both locally, nationally and for export but after 1860 there was a rapid decline in the number of men employed in lead mining. One exception to this decline was the Mill Close Mine at Darley Dale.
By the late 1850’s Millclose was on the verge of being worked out but was re-opened in 1859 by E M Wass, who also owned Lea Lead Works, and the pipe vein was worked northwards into a new ore rich area providing many more productive years. Then in 1938 the workings broke into an enormous water table, either an underground lake or river and the mine flooded. After great efforts to overcome this deluge the mine finally closed in 1940 as despite all their efforts the water still poured in – said to be at 2,000 litres per minute. The mine finally closed just before the Second World War due to no new ore sources being found, the low market price of lead and the immense costs of pumping water to enable further access.
Millclose mine yielded well over half a million tons of lead ore and almost 100,000 tons of zinc ore in its century of life. About half of the lead tonnage was actually produced in the 1920s with a further 140,000 tons by re-working the spoil heaps in the 1930s and 40s.
With the exception of wool, lead was the most important contributor to the national economy of 17th century Britain.