User:Elycadiz/Mining in Roman Britain

[Feedback from Dr Austen - this is a really good start Lovely and, on the whole, maintains that crucial neutral tone throughout. What is missing though is the CITATIONS! These are absolutely crucial for a Wikipedia article and need to be added throughout - otherwise we will not be able to publish your material. If I could suggest a particular area that might be added - it might be nice to include further exploration of a couple of the mining sites if possible? You may also want to explore WHY mining was so crucial to Roman Britain i.e. the importance of natural resources to the colonization effort - gave the Romans resources = money!]

**To whoever's reviewing this article: I realized you might have had a hard time accessing my sandbox so I just made this page. Hopefully this helps. :)

Mining was one of the most prosperous activities in Roman Britain. Britain was rich in resources such as copper, gold, iron, lead, salt, silver, and tin, materials in high demand in the Roman Empire. Sufficient supply of metals was needed to fulfill the demand for coinage and luxury artefacts by the elite. The Romans started panning and puddling for gold. The abundance of mineral resources in the British Isles was probably one of the reasons for the Roman conquest of Britain. They were able to use advanced technology to find, develop and extract valuable minerals on a scale unequaled until the Middle ages.

Lead mining[edit]

Lead was essential to the smooth running of the Roman Empire. It was used for piping for aqueducts and plumbing, pewter, coffins, and gutters for villas, as well as a source of the silver that sometimes occurred in the same mineral deposits. Fifty-two sheets of Mendip lead still line the great bath at Bath which is a few miles from Charterhouse (see below).

The largest Roman lead mines were located in or near the Rio Tinto (river) in southern Hispania. In Britannia the largest sources were at Mendip, South West England and especially at Charterhouse. In A.D. 49, six years after the invasion and conquest of Britain, the Romans had the lead mines of Mendip and those of Derbyshire, Shropshire, Yorkshire and Wales running at full shift. By A.D.70, Britain had surpassed Hispania as the leading lead-producing province. The Spanish soon lodged a complaint with the Emperor Vespasian, who in turn put limits on the amount of lead being produced in Britain. However British lead production continued to increase and ingots (or pigs) of lead have been found datable to the late second - early third century. Research has found that British lead (i.e. Somerset lead) was used in Pompeii - the town destroyed in the eruption of Vesuvius in A.D.79.

Roman lead mined from Mendips, Derbyshire, Durnham and Northumberland were mainly sourced for its lead content. The silver content of ores from this country was significantly lower than Athenian lead-silver mines and Asia Minor mines.

Smelting is used to convert lead into its purest form. The extraction of lead occurs in a double decomposition reaction as the components of galena are decomposed to create lead. THe reducing agent in this reaction is the sulfide and fuel is only needed for high temperature maintenance. Lead must first be converted to its oxide form by roasting below 800C using domestic fire, charcoal or dry wood. This is done easily as lead melts at 327C. Lead oxide (PbO) is the oxide form of galena which reacts with the unroasted form lead sulfide (PbS) to form lead (Pb) and sulfur dioxide (SO2).

Details on Roman lead smelting has not been published although open hearths were found in Mendips by Rahtz and Boon. These remains contained smelted and unsmelted ores. The remains of first century smelting was found in Pentre, Ffwrndan. Although this discovery was valuable, reconstruction of the remains were impossible due to damage. An extracted ore from the site had a lead content of 3 oz. 5 dwt. per ton and another piece contained 9 oz. 16 dwt per ton of lead.

Silver extraction[edit]

The most important use of lead was the extraction of silver. Lead and silver were often found together in the form of galena, an abundant lead ore. Galena is mined in the form of cubes and concentrated by removing the ore-bearing rocks. It is often recognized by its high density and dark colour. The Roman economy was based on silver, as the majority of higher value coins were minted from the precious metal. British ores found in Laurion, Greece had a low silver content compared to the ores mined from other locations. The Romans used the term Britain silver for these lead mines.

Galena was mined for its lead and silver content.

The process of extraction, cupellation, was fairly simple. First, the ore was smelted until the lead, which contained the silver, separated from the rock. The lead was removed, and further heated up to 1100° Celsius using hand bellows. At this point, the silver was separated from the lead (the lead, in the form of litharge, was either blown off the molten surface or absorbed into bone ash crucibles; the litharge was re-smelted to recover the lead), and was put into moulds which, when cooled, would form ingots that were to be sent all over the Roman Empire for minting. Silchester, Wroxeter and Hengisbury Head were a known location for Roman cupellation remains.

When inflation took hold in the third century A.D. and official coins began to be minted made of bronze with a silver wash, two counterfeit mints appeared in Somerset - one on the Polden Hills just south of the Mendips, and the other at Whitchurch, Bristol to the north. These mints, using Mendip silver, produced coins which were superior in silver content to those issued by the official Empire mints. Samples of these coins and of their moulds can be seen in the Museum of Somerset in Taunton Castle.

Copper Mining

Copper alloy was mostly utilized in Roman Britain to make brooches, spoons, coins, statuettes and other things needed for an armour . It was rarely used in it purest form, thus, it always contained other elements such as tin, zinc or lead, which added various properties to the alloy. Pure copper has a pinkish colour and with the addition of a few percentage of other elements, its colour may change to pale brown, white or yellow.

The composition of copper alloy differed from region to region in the Roman Empire. Leaded and unleaded bronze were mainly used in the Mediterranean period. These types of bronze were produced by adding tin and lead to copper in certain amounts that depended on the type of object being produced. 5% to 15% of tin was added to bronze for casting of most objects. Mirrors, on the other hand, were made with bronze that had approximately 20% tin as it needed a speculum, which is a silvery-white alloy.

Another copper alloy, brass, was not widely used in casting objects as it was very difficult to produce. The production of brass did not begin until the development of the cementation process. In this process, zinc ore and pure copper are heated in a sealed crucible. As the zinc ore is turned into zinc, the seal in the crucible traps the zinc vapour inside, which will then mix with the pure copper to produce brass. The production of brass through this process was controlled by 'state monopoly' as brass was being utilized for coins and military equipments. The production of sestertii and dupondii from brass was taken up by the Augustan period and brass was also utilized in production of other military fittings such as lorica segmentata.

Gold mining[edit]

Development of Dolaucothi Gold Mines The aqueducts at Dolaucothi

The native form of silver is gold, which can be mined in Linlithgow in Scotland, Cornwall and other British Isles locations. Melting was necessary for this form of native silver as it is found in a form of leaves or filaments.

Britain's gold mines were located in Wales at Dolaucothi. The Romans discovered the Dolaucothi vein soon after their invasion, and they used hydraulic mining methods to prospect the hillsides before discovering rich veins of gold-bearing quartzite. The remains of several aqueducts and water tanks above the mine are still visible today. The tanks were used to hold water for hushing during prospecting for veins, and involved releasing a wave of water to scour the ground and remove overburden, and expose the bedrock. If a vein was found, then it would be attacked using fire-setting, a method which involved building a fire against the rock. When the hot rock was quenched with water, it could be broken up easily, and the barren debris swept away using another wave of water. The technique produced numerous opencasts which are still visible in the hills above Pumsaint or Luentinum today. A fort, settlement and bath-house were set up nearby in the Cothi Valley. The methods were probably used elsewhere for lead and tin mining, and indeed, were used widely before explosives made them redundant. Hydraulic mining is however, still used for the extraction of alluvial tin.

Long drainage adits were dug into one of the hills at Dolaucothi, after opencast mining methods were no longer effective. Once the ore was removed, it would be crushed by heavy hammers, probably automated by a water wheel until reduced to a fine dust. Then, the dust would be washed in a stream of water where the rocks and other debris would be removed, the gold dust and flakes collected, and smelted into ingots. The ingots would be sent all across the Roman world, where they would be minted or put into vaults

Romans were also drawn to Gallaecia and Asturia as it was believed to hold the finest gold fields. The beginning of Augustus' rule over these areas also commenced the utilization of the land's resources. These areas were believed to provide 20,000 lbs of gold solely from the alluvial terraces, aside from the gold obtained from hard-rock deposits and placer-mining. The amount of gold being mined in these regions was too vast that the procurator was not able to manage the lands due to the expense that came with it. An equestrian procurator, along with imperial freedmen and military contingents managed the gold mines.

Iron mining[edit]

Armours, construction tools, agricultural tools and other building materials were mostly made of iron, thus, making iron one of the most in demand metals at all times. There was always a supply for iron in many parts of the Roman Empire to allow for self sufficiency.

There were many iron mines in Roman Britain. The index to the Ordnance Survey Map of Roman Britain lists 33 iron mines: 67% of these are in the Weald and 15% in the Forest of Dean. Because iron ores were widespread and iron was relatively cheap, the location of iron mines was often determined by the availability of wood, which Britain had in abundance, to make charcoal smelting fuel. Great amounts of iron were needed for the Roman war machine, and Britain was the perfect place to fill that need.

Many underground mines were constructed by the Romans. Once the raw ore was removed from the mine, it would be crushed, then washed. The less dense rock would wash away, leaving behind the iron oxide, which would then be smelted using the bloomery method. The iron was heated up to 1500 °C using charcoal. The remaining slag was removed and generally dumped.

After being smelted, the iron was sent to forges, where it was reheated, and formed into weapons or other useful items.

Roman iron was thought to held more value than other metals due to the tedious production through direct or bloomery smelting. A recovered Vindolanda tablet documents the purchase of 90 Roman pounds of iron for 32 denarii by a man named Ascanius. This amounted to 1.1 denarii per kilogram of iron.

Fall of Metal Economy

The Roman economy depended on the abundant metals that were mined in many regions. Approximately 100,000 tons of led and 15,000 tons of copper were sourced within the imperial territory and about 2,250 tons of iron was produced each year. This abundance and extensive production of metal contributed to the pollution in Greenland ice, and it also affected the metal industry as more and more inexpensive metals were available throughout the empire. The production and availability of smelted metal started to ceases during the late fourth century as the Romano-British economy began to untangle. The only solution for people who needs metals as part of their livelihood was to scavenge for metal scraps. This was evident from the excavated odd metalworks from Southwark and Ickham. By the end of fourth century Britain was unable to sustain the need for metals as the production of new ceased, thus, many metal-working sites were abandoned and skilled workers left with no jobs.