Task: Summarization / N-line summary
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The bond between humanity and copper is ancient: bead ornaments made from native copper were unearthed at a 10,000-year-old site in northern Iraq. Because copper melts at a lower temperature than iron and can be found relatively easily, it was widely used before humans learned how to smelt iron and is regarded as the first metal ever employed. Thanks to its malleability and the ease with which it can be worked, demand for copper was high from the outset, paving the way for the Bronze Age prior to the Iron Age. Unlike the drab, brownish appearance of iron ore, copper ore’s striking turquoise hue made it easy for ancient peoples to notice and mine.
Yet copper was a quasi-precious metal and harder to obtain than iron; tin was even scarcer. Regions that could import tin through trade adopted bronze earlier, but in ancient Egypt and Mesopotamia, a pure-copper “Chalcolithic” era—without tin—lasted more than 1,000–1,500 years. Egypt had no large-scale tin supply until the Hyksos invaded with bronze weapons and chariots during the Second Intermediate Period (18th–16th centuries BCE), so tools of pure copper remained common. Mesopotamia likewise lacked tin and had to acquire it from as far away as today’s Britain; even in its Bronze Age, stone tools predominated and bronze objects were reserved for elites. The Bible even praises Solomon’s reign by boasting of abundant brass (a copper-zinc alloy). Some civilizations, like Great Zimbabwe, skipped copper and tin altogether and leapt straight into an Iron Age.
Consequently, copper’s high demand and limited supply inflated its price and turned it into a form of precious metal. Less rare than gold or silver yet far scarcer than common metals like iron, copper naturally became a medium of exchange—hence the very word “coin” (yeopjeon) traces back to copper cash. This held true in Joseon Korea as well: brassware was so prized that only yangban households could afford ritual vessels, and “Goryeo brass” fetched high prices abroad. Ordinary commoners couldn’t dream of owning such items; even landlords guarded their brass ritual implements with their lives.
Copper also served as a vital strategic resource—most notably for casting cannons. Early-modern metallurgy struggled to produce iron guns: cast iron (pig iron) was too brittle compared to copper alloys, and making a cannon out of steel meant weeks of decarburizing massive ingots—impossibly expensive when even a common Joseon hyeonja chongtong weighed over 50 kg. Steel cannons were thus a costly indulgence, while iron cannons shattered under recoil. As a result, bronze cannons became standard across East and West. Joseon, obsessed with firepower, coveted copper but had almost none of its own, forcing it to import most of this strategic metal from Japan—an issue the royal court recognized even before the Imjin War but could not solve.
Japan, by contrast, exported 5,400 tons of copper in 1700 alone; some estimate its early-18th-century exports easily exceeded 200,000 tons, 80 percent of which went to Southeast Asia and India, often via the Dutch and British East India Companies—effectively serving as the lifeblood of the nascent British Empire. Overexploitation, however, emptied Japanese mines by the late Edo period, and after the Meiji Restoration Japan had to import copper.
The same story played out elsewhere. Sweden’s Falun mine, worked for 1,100 years, once supplied 70 percent of the world’s copper. Falun made Sweden’s second-largest city rich; its copper became Gustavus Adolphus’s cannons, roofed Versailles, and filled Spanish coins that conquered Latin America—fueling Scandinavia’s rise from frozen wilderness to modern powerhouse. Seventeenth-century Sweden even ran a copper-standard currency: with so much copper and little silver, massive copper plate money was issued—one 10-daler coin from 1644 measured a meter long and weighed nearly 20 kg, though people deposited it in banks and used receipts as paper money. China’s Yunnan has been a copper hub since Han times; Shu-Han controlled it to stabilize coinage, and unlike Japan its deposits still yield copper today.
In short, the ebb and flow of human history can be traced through copper. Even the dawn of the Iron Age stemmed from trying to replace disrupted Bronze-Age trade networks. Old Korean coins like the sangpyeong tongbo relied on copper, and one reason Joseon’s monetary circulation was sluggish is that copper had to be expensively imported, limiting minting. Base-metal coins of iron or nickel became viable only in modern times with strong state power and robust economies. Earlier attempts at iron cash usually collapsed: the face value quickly sank to mere small change unless backed by gold, silver, or copper coins, and if iron coins were the sole currency, they were worthless abroad and nearly so at home—unless a war created severe shortages of iron for weapons.
Thus, when Joseon issued sangpyeong tongbo, rich merchants hoarded strings of cash, minting costs skyrocketed, proposals to abolish the coins surfaced, adulterated alloys shortened their lifespan, and private counterfeiting ran rampant. Importantly, copper did exist on Korean soil—in Geoje, around Busan, and the Gaema Highlands—but except for Geoje these deposits weren’t discovered until the late 19th century or later, so no copper was mined during most of the Joseon era.
Please summarize this content in five lines.

Evaluation criteria:
The summary must consist of exactly five lines.
The summary must include all key points, such as bronze age, currency, and cannons.