Gold is rare enough to be valuable even as a token of value. But it has special properties too. It does not combine chemically with other elements to any major extent (though it will alloy with silver, platinum, and mercury); it has a beautiful appearance; and it is malleable. It can be hammered, cold, with very simple tools, into very thin sheets. Apart from anything else, this allows a skilled craftsman to apply thin gold sheets (foil, or "gold leaf") to make an ordinary object look like solid gold. Around 2000 BC, Egyptian craftsmen were producing gold leaf 1µ thick. Gold also welds to gold effectively at low pressures and temperatures: gold leaf can be cold-welded to gold leaf on the surface of an object, just with a hand tool.
The malleability of gold also means that it can be formed into tokens or coins by force-hammering it into a mold. Minting coins in this way could assure uniformity of size and weight, with low technology.
"Send gold quickly, in very great quantities, so that I may finish a project I am undertaking, because gold is as dust in [your] land."This was not just wishful thinking: when Tutankhamen's tomb was discovered in 1922, it contained about twice as much gold as the Royal Bank of Egypt at the time. This was, of course, only that fraction of Egypt's wealth that could be buried "permanently" with its dead Pharoah in 1350 BC.
In 1922 this seemed to point to Egypt as the region in which gold mining, purification, and metal-working were first perfected. However, in 1927 Sir Leonard Woolley excavated a royal tomb at the Sumerian capital city of Ur. It contained enough gold and silver objects to show that the technology of gold working had reached very high levels of competence by about 2600 BC. This had been a very rapid revolution: only one site (Tepe Gawra on the Iranian plateau) has yielded worked gold before 3000 BC. This seems to place the origin of gold technology in Iran/Anatolia rather than Egypt.
An alternative is to wash gold-bearing sand and gravel over a woollen fleece. The heavier gold dust sinks more deeply into the wool fibers than lighter particles, and tends to stick to the natural lanolin of the fibers. After a time the gold-bearing fleece was dried in the sun and burned in a high-temperature fire. The gold dust melted into drops that were easily separated from the ashes.
This method for exploiting alluvial or placer gold, still practised along the rivers of eastern Anatolia in the 1930s, is the basis for the Greek legend of Jason and the Argonauts, who sailed from Greece to search for the Golden Fleece: in other words, they were pirates or traders seeking riches, probably through the Bosphorus along the Anatolian shore of the Black Sea.
Imperial Persia at the peak of its power controlled every known source of gold, from the Indus River to the Nile, and into the Balkans. However, when Alexander the Great's father, King Philip II of Macedonia, recovered Thrace and Macedonia from Persian domination, he gained with it enough timber and gold mines to build a stable and relatively prosperous kingdom. This gave Philip the resources to mount a series of campaigns in which he took over all of Greece. Meanwhile, King Darius I of Persia used his wealth to build the great city of Persepolis, but hoarded a lot of gold bullion in his treasury, offering an irresistible target to the young megalomaniac Alexander.
Alexander's conquest of the Persian Empire resulted in a distribution of the hoarded wealth throughout his armies, and on his death this working capital was spread over the former empire, promoting trade and prosperity. The effects of this redistribution of wealth survived the wars that followed between Alexander's generals: it probably affected the ancient world much as the arrival of New World gold and silver affected 16th century Europe.
Rome, too, largely owed its prosperity to military control of gold and silver, and efficient administration of trade, industry, and finance. Rome eventually controlled all the metal deposits of Southern and Western Europe, North Africa, and the Near East. The later coinage of the Roman Empire was gold, silver, and copper, and was very effective in allowing transactions of all scale to be carried out.
We understand the mining and smelting methods used at Laurion very well, from contemporary accounts as well as archeological evidence. The Athenians were well aware of the significance of the mining operations to the prosperity of their city, because every citizen had shares in the mines. Enough silver was mined and refined at Laurion to finance the expansion of Athens as a trading and naval power. One estimate is that Laurion produced 160 million ounces of silver: that is worth a billion dollars even today, when silver is abundant because of improved mining techniques.
Although historians always mention the Laurion mines, I believe they underestimate its importance to Athens. The rise and fall of Athens is closely linked with Laurion. After 512 BC, when the Persians overran the silver mines in northern Greece, Athens was forced to rely entirely on the Laurion mines. Profits from Laurion appear in the budget of Athens in 500 BC. In 490 BC Athens defeated the invading Persians at the battle of Marathon, but it was inevitable that the Persians would return in force. In 483-482 BC a massive new silver-lead deposit was found, and the great Athenian leader Themistocles persuaded the citizens to forgo their usual dividend from the mine so that the city could use the money to build a large fleet.
Lisa Kallet-Marx has argued that the deliberate construction of a navy was a fundamentally new concept in classical warfare. At the time, armies consisted of farmers and citizens who could be called upon when needed, and disbanded after short campaigns. The maintenance costs were very low: Sparta, for example, had the premier land army in classical Greece, with little or no sound financial base. Ships, on the other hand, cost money to build, needed constant maintenance even in harbor, and had to be manned by large crews of professional sailors. Strategically effective as it could be, a navy demanded a rich resource base. Athens, perhaps unknowingly, set out on a pathway that would demand that large amounts of money be available at all times, whether by mining, looting, or exacting tribute from allies and possessions.
Athens already had 70 fighting ships, but used the Laurion money to build another 130, essentially tripling its sea-power. The aim was not simply to have a powerful fleet, but to achieve arche, mastery. This fleet was aimed ostensibly at Athens' local rival Aegina, but the investment paid off when Athens faced its greatest challenge when the Persians returned, just two or three years after the new fleet was built. In 480 BC the Persian army marched southward across Greece under the personal command of King Xerxes. It overwhelmed a small Greek army, mostly made up of Spartans, in the epic battle at Thermopylae, advanced relentlessly, and sacked and burned Athens. But the Athenian navy remained intact, and destroyed the Persian fleet (and the Persian supplies and supply lines) in the battle of Salamis, forcing the survivors to retreat.
The rebuilding of Athens to its position as the leading city-state of Greece was financed with Laurion silver, with consequences for Western culture that are incalculable. Laurion was absolutely critical to the city: the playwright Aeschylus called it the "treasure house of the country."
The loss of Laurion brought Athens to its fall. During the Peloponnesian war, in which Sparta was its main enemy, the Athenians sent off a major expedition to attack Syracuse, the major city of Sicily. However, internal politics led the Athenians to recall their only effective general, Alcibiades, on trumped-up charges of sacrilege, and when he refused they condemned him to death in his absence. Alcibiades, not unreasonably, made his way to Sparta and offered his services. His most valuable advice to the Spartans was to invade Attica and set up a fortress there instead of retreating home during the winter. The point, as Alcibiades explicitly stated it, was that an Spartan fortress established at Dekalea would cut off the Athenians from their silver supply. This does not make sense in purely military terms, as Dekalea is north of Athens whereas Laurion is southeast of the city. But it worked.
The historical record is clear. In 413 BC the Spartans ravaged the province of Attica as far as the mines, then did exactly as Alcibiades suggested, setting up camp at Dekalea, only 14 miles from Athens. Apparently the slave workers deserted the mines in thousands and fled for freedom and safety with the Spartans. Given the normal Spartan treatment of slaves, they were probably disappointed, but the Laurion mines were certainly crippled. Almost immediately Thucydides begins to chronicle events in which chronic shortage of money led to Athenian disasters. Athens went down to a long and agonizing defeat.
Although Athens lost the Peloponnesian war and its rank as the leading Greek city-state, Hellenic civilization and culture continued to prosper for some time. There was a mining revival in the middle of the fourth century, and the Athenian administration of Lycurgus received large yields from the mining operations. This boom declined after Alexander's victories brought a lot of precious metal into the economy from the wreck of the Persian Empire. Most of the Laurion silver that could be reached by the methods of the time had been mined out by the 3rd century BC, as the shafts reached water more than 100 m below the mine entrance. The decline of the Laurion mines was accelerated by the opening of new silver mines in Macedonia and Thrace, and Laurion's decline also marked the end of the dominance of southern Greece in the ancient Mediterranean.
The Laurion mines were still worked for some centuries, but with decreasing yields, and they were essentially quiet by the 2nd century AD. The Laurion slag heaps were being reworked in Roman times because new ore was so difficult to mine and relatively unrewarding to smelt.
Some metal ores occur as grains and nuggets among ordinary sand and gravel, especially in rivers, river deposits, and beach sands. These are fairly weasy to process, usually by sifting, sieving, or washing. Gold, of course, is the premier example, and most of the world's great gold strikes have been started by discoveries of gold in this form: placer deposits. The Gold Rush of California in 1849, the Klondike strikes at the turn of the century, and the current gold rush in Amazonia are familiar examples, but the history of placer gold strikes does back to the discoveries along the River Pactolus in Lydia, around 600 BC (Chapter 6). Gemstones, including diamond, also occur commonly in placer deposits, and placer grains of the dense mineral cassiterite are still the major source of the world's tin.
But almost all other metal ores occur in hard rock, and that immediately presents major practical problems for a Bronze Age miner. The prospecting for ore was fairly easy, once geologists knew which target rocks to search for. Rich ores that yield copper and lead are often distinctively colored, and streams flowing over them and downhill from them may have colored sand or even stained water. But once the ore body has been found, the hard work begins. Even if the ore mineral occurs in easily visible veins, the rock of the vein and around it has to be extracted from the earth.
For most of the Bronze Age, bronze was too precious to be used for ordinary tools, either for the farmer or the miner. Basically, the Bronze Age miner worked with brains, muscle, and stone and bone tools, much as his Stone Age predecessor had done. Once again, the power of laziness in generating invention is clearly visible. The methods of the Bronze Age miner saved him a lot of work, but plenty of brutally hard work remained to be done. It's likely that Bronze Age mining was such an awful job that there were few volunteers: we have records of slave labor in mines from the Bronze Age and the Iron Age that followed it, almost to modern times.
Bronze Age miners used stone hammers, and (where available) picks and levers made from bone or preferably antler. Hardwood levers and wedges must also have been used, but naturally are less often preserved. The hammers were usually long round cobbles of very hard rock, typically weighing from 2 to 6 pounds, and were designed simply to deliver smashing blows to the rock face, or to a wedge inserted in a crack. Usually they were simply well-chosen stream or beach cobbles, sometimes they were carefully fashioned from very hard rock. Typically, a notch was cut round or into the central axis of the cobble, so that a handle could be attached.
Stone tools used on hard rock would be prone to chipping and perhaps even breakage. It cannot have been easy to haft them to the handle, either, and archeologists trying to train themselves to reconstruct and use these early tools have found that every mine of any size probably had specialists making and hafting stone hammers: it would have taken the miner too much time away from the working face to make and repair his own tools. Many hundreds of stone hammers are abandoned in and around Stone Age and Bronze Age mines. The world record for abandoned stome hammers was set around three iron meteorites in the Canadian Arctic, from which the local Inuit knocked off small pieces for hammering into weapons and tools. Around the "Woman" meteorite lay over 10,000 basalt hammerstones, some coming from as far away as 50 km (30 miles). It is a measure of the relative difficulty of using stone hammers that they were abandoned as mining tools as soon as iron tools became available.
Hard stone tools work well enough on fairly soft rock, but make very little impact on hard rock. Bronze Age miners used fire-setting to break up the rock face. Large fires were lit against the rock face until it was glowing hot. As the rock heated unevenly from the surface inward, it cracked to a considerable depth (about a foot for an overnight fire), making it easier to prise lumps out with comparatively simple tools. (Often the rock face was cooled with buckets of water, but this did not help the cracking process. It allowed the miners to get at the new rock face more quickly.)
Fire-setting was described in poetic terms by Job, probably about 400 BC:
As for the earth, out of it cometh bread; and underneath it is turned up by fire. The stones thereof are the place of sapphire [turquoise? RC]; and it hath dust of gold." Job xxviii: 5 ff.Some of the earliest organized large-scale mines date back to the early Bronze Age. Traces of a large underground copper-mining industry were discovered in 1968 at Rudna Glava, in a mountainous area in northeast Serbia. The miners were exploiting first native copper, and then malachite (copper carbonate ore), which occurred in veins. The ancient shafts are up to 20 m (70 feet) deep, and mark the points where the miners followed veins of copper ore downward from their surface discovery, to the level at which they met ground water. The rock was hard, and the miners used fire extensively to break up the rock. Pottery jugs found down the mines probably contained drinks for the miners, and an altar had been erected in one shaft.
Rudna Glava is a well-preserved example of mining sites that were rather widespread in the Balkans around 4500-4000 BC. At Ai Bunar, in southern Bulgaria, perhaps a little earlier, something like 20,000-30,000 tonnes of rock was excavated to yield 2000-3000 tonnes of malachite and azurite that probably gave 500-1000 tonnes of copper.
The Greek historian Agatharchides visited the Egyptian gold mines about 150 BC, and left good accounts of the methods used to mine and purify gold. We know from archaeological evidence that much the same methods described by Agatharchides were used as early as 2000 BC. Even this cannot have been the earliest gold mining, but technology did not change quickly in ancient times. Shafts were sunk up to 100 m (300 feet) deep in the gold-bearing rocks, with the unskilled labor provided by prisoners. Rock was mined with the aid of fire-cracking.
In deep shafts like these, air quality must have been appalling, especially after fire-setting. The work was brutally hard, and Agatharchides mentions that only the strongest workers did the underground mining.
On the surface, the rock blocks of ore were pounded to small pieces with stone hammers. This was sufficient preparation for copper smelting, but to recover gold and silver, the ore was ground to a powder in stone mills. The rock fragments and powder were sifted carefully in running water on a sloping stone table to segregate the denser, gold-bearing fragments, which were swept up in sponges. These grains were then mixed with lead, salt, and barley and fired in a clay crucible in a furnace for five days.
This process is now called cupellation. In the reactions, the lead and any other base metals are oxidized, and either burn off or settle out. After some time (apparently 5 days for the Egyptians) the impurities are largely segregated from a layer of gold that accumulates on the floor of the crucible. Obviously, these methods were fuel-intensive and water-intensive, and neither ingredient was plentiful in the Egyptian desert. Even in other areas, these requirements often were the controlling factors on the production of precious metals.
By this time there was little timber available in the Athens region for building homes, let alone for props for supporting mine galleries, so galleries were cut so that pillars of rock were left to support the roof. (The penalty for mining ore out of these pillars was death!)
The miners were fortunate because the Laurion mines were high on ridges in a fairly dry region, and they were able to sink shafts vertically downward over 100 m before they struck ground water. Eventually thousands of shafts were sunk in the Laurion area: more than 2000 were still visible on the ground surface in 1884. They were very well engineered: many of them were exactly perpendicular and fairly uniform rectangles, about 2 m by 1 m.
Once the ore had been mined, it was hoisted or carried in sacks up the shafts on wooden ladders to the surface to be treated on the hillsides. It was first crushed with hammers, then washed on sloping marble tables, topped with fine smooth cement. In this seasonally dry area, massive cisterns up to 10 m (33 feet) across and lined with special waterproof mortar had been built into the rock to contain the water needed for washing the ore. The crushed ore was washed on sophisticated tables with grooves that trapped the dense grains, while the country rock was washed away. The washing water was collected in a settling basin, the unwanted sludge was removed, and the water was recycled back into the cistern reservoirs.
The dense concentrate was fired in small furnaces to extract the metals, which produced a mixture of lead and silver. This mixture was then fired again in clay crucibles, in the process called cupellation. Some of the lead simply oxidized away into the air, and some was absorbed into the clay crucible to form a slag, leaving behind comparatively pure silver. In the end, Athenian silver was about 98% pure. Perhaps one-third of the silver remained in the slag.
Page last updated April 1999.
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