Why do Copper Coins Change Colors?

If you’re a coin collector or just happen to handle change a lot, you’ve probably seen old copper coins in various colors. From white to green to blue! Why do these coins take on so many different colors? One may think it’s because of something that got stuck to it, maybe a candy wrapper or some sticky food but these colors are actually naturally occurring!

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pile of various cull wheat cents

There are two common forms of attack upon these older metals. In the milder case, a metal may tarnish. “Tarnish” is a thin coating on the surface of a metal and is usually very uniform and does not often destroy the intended purpose of the metal. “Corrosion,” on the other hand, is often not uniform, but may cause pits and may reach such proportions as to destroy the metallic object so that it cannot be used for its intended purpose.

In dry air, even tarnishing takes place quite slowly; however, with the usual atmosphere around us, the humidity accelerates the tarnishing process. The lowest oxide level of copper is cuprous oxide, or cuprite. Its color is pink. Barely noticeable at first, a penny becomes darker over time due to the tarnish layer thickening, as well as the continued oxidation to the black cupric oxide, tenorite.

Over time, and upon repeated or prolonged exposure to moisture in the presence of dissolved acidic substances, such as carbon dioxide and the polluting substances found in acid rain, tarnished copper turns green. Among these acid substances are the oxides of sulfur and the oxides of nitrogen. Reacting with moisture, they form dilute solutions of strong acids.

Copper that is exposed to open air will corrode and undergo a series of chemical reactions that lead to the development of a patina – a coating of copper oxide molecules which actually protects the metal beneath. Over time, copper transitions from its shiny brown color to a darker brown shade.

After many years it transitions into blues. At an even later stage the formation of copper sulfate, carbonate and chloride salts in varying concentrations turns the surface green. There are several factors which affect the amount of time these processes take including moisture, temperature, and the level of pollution. The formation of the natural green patina seen on copper roofs and statues takes a very long time, but methods have been developed to speed the process up using chemical reactions.

Statue_of_Liberty_7Coins aren’t the only place we often see this chemical reaction take place; we’ve all seen the greenish blue Statue of Liberty, but did you know Lady Liberty was once a copper color? That’s right, the famous statue was once covered in a thin layer of copper and was bronze when she first arrived in the United States from France. Acid in rain covers the Statue of Liberty whenever storms hit New York, and her exposure to oxygen from being in the middle of the ocean gradually turned her blue over the years.

Swedish Daler Plate Money

When we think of coins we typically think of fairly small circular slabs of various types of medal. Some are slightly larger than others, have ridges on the edges, or even have a hole in the middle; what we don’t imagine is a large ‘plate’ of copper that weighs 1.5kg and measures 18.5 x 20cm. The Swedish riksdaler plate, was first minted in 1624 and was the currency of Sweden for several years.

From 1624, daler were issued in copper as well as silver. Because of the low value of copper, large plate money (plåtmynt) was issued. These were rectangular pieces of copper weighing, in some cases, several kilograms. (The largest one is worth 10 daler and weighs almost 20 kilograms (44 lb)). They circulated until 1776. As silver became scarce, the silver daler rose in value relative to the copper daler, with the exchange rate between the two eventually being set at a ratio of 3 to 1.

Use of copper for plate coinage began during the reign of Gustav II Adolf (1611-1632). The copper mine in Falun (Dalarna county) produced about 2/3 of the worlds copper at the time and the use of copper coinage was an attempt to control the price of copper to the advantage of Sweden.


Mining Tools in the Falun Mine

There are no written accounts establishing exactly when mining operations at Falun Mine began. Archaeological and geological studies indicate, with considerable uncertainty, that mining operations started sometime around the year 1000. No significant activities had begun before 850, but the mine was definitely operating by 1080. Objects from the 10th century have been found containing copper from the mine. In the beginning, operations were of a small scale, with local farmers gathering ore, smelting it, and using the metal for household needs.

Around the time of Magnus III, king of Sweden from 1275 to 1290, a more professional operation began to take place. Nobles and foreign merchants from Lübeck had taken over from farmers. The merchants transported and sold the copper in Europe but also influenced the operations and developed the methods and technology used for mining. The first written document about the mine is from 1288; it records that, in exchange for an estate, the Bishop of Västerås acquired a 12.5% interest in the mine.

By the mid 14th century, the mine had grown into a vital national resource, and a large part of the revenues for the Swedish state in the coming centuries would be from the mine. The then king, Magnus IV, visited the area personally and drafted a charter for mining operations, ensuring the financial interest of the sovereign.

Sweden had a virtual monopoly on copper which it retained throughout the 17th century. The only other country with a comparable copper output was Japan, but European imports from Japan were insignificant. In 1690, Erik Odhelius, a prominent metallurgist, was dispatched by the King to survey the European metal market. Although copper production had already begun to decline by the time he made his report, something Odhelius made no secret of, he stated, “For the production of copper Sweden has always been like a mother, and although in many places within and without Europe some copper is extracted it counts for nothing next to the abundance of Swedish copper”.

By modern standards, however, the output was not large. Peak production barely reached 3,000 tonnes of copper per year, falling to less than 2,000 tonnes by 1665; from 1710–1720 it was barely 1,000 tonnes per year. Present worldwide copper production is 18.3 million tons per year


8 Daler Plate in the British Museum.

In 1643, the first plate money was issued in the denomination of 10 Daler SM. These plates were approximately 13 by 27 inches in size and weighed 43 pounds. Today, these first plates are rare and may only be found in museums. The Coinage Act of 1649 stipulated plates in denominations of 1, 2, 4 and 8 silver Dalers and after 1684 the denominations were 1/2, 1, 2 and 4 silver Dalers. Metal content also decreased over time such that 1 Daler SM weighed 3.5 pounds in 1660 and settled at 1.7 pounds in 1715. The last year plates were produced in large quantity was 1759 with some 2 Daler plates in 1760. There are also rare plates from 1768.

The plates have four corner stamps bearing the name or initials of the current monarch and the year of issue. The center stamp bears the denomination and the reverse is blank. Some plates have an additional stamp due to redenomination. Many plates show signs of the manufacturing process with hammer marks; the copper was formed into sheets of necessary thickness, cut to size with shears, and  then stamped. This was hand work using large tools and gives each plate a unique character.

It is hard for most people to imagine using such coins in commerce. Illustrations of the era depict citizens with sacks of copper plates over their back or pulling a load of plates to the bank on a sled. This inconvenience was the catalyst for the creation of the world’s first bank notes. In the 1660’s, a bank was formed where plates could be deposited in return for a paper certificate of value. This paper money was an instrument which could be exchanged in commerce and the value repaid to the bearer in copper at the bank. This led to the creation of the world’s first central bank, Sveriges Riksbank (The National Bank of Sweden).

Today, around 11,000 pieces of plate money are known to exist across all years and denominations. Approximately 3,000 of these were recovered from the wreck of the trading ship Nicobar, which was discovered and salvaged in the 1980’s off the coast of southern Africa. On July 23, 1782 the Nicobar left Sweden with a load of recently undenominated plates to be traded at Danish posts on the Indian coast and the Nicobar Islands, east of India. On the way to the Cape of Good Hope it was forced to replenish on the west coast of Africa at False Bay, on May 20, 1783. On July 10, shortly after leaving False Bay, it was wrecked in a storm. Two hundred years later, local fishermen found the wreck.

Being such a numismatic oddity, plates are desired by collectors with widely varying interests. Prices range from a few hundred dollars for smaller sea water damaged examples to several thousand dollars for scarcer 4 Daler plates in nice condition.

The Mythical Lebbo Coin

lebbo_coin_backYou may have heard of the myth of the Lebbo Coin and it’s almost magical capabilities. Also referred to as a Copper Iridium Coin, a “Rice Pulling” Coin, or Navagraha Lebbos, the Lebbo Coin is a mythical coin that has its roots in ancient India.

The story of the Lebbo Coin goes, in the year 1616 AD, there was a Grahakutami (A complete solar eclipse) which lasted for more than 5 hours in India. The British, with the help of Indian Rishis minted Copper coins with Copper Iridium metal in assorted weights and sizes. It is said that there are only 16 pieces of the coins made total. In order to preserve the precious Lebbos, the Rishis engraved the currency denomination prevalent on one side and nine planets on the other side.

The planets engraved on the coins were the Sun (Surya), Moon (Chandra), Mars (Mangla), Mercury (Budha), Neptune (Guru), Jupiter (Sugra), Saturn (Sani), Uranus (Ragu) and Venus (Kethu). The planets were minted to be all interconnected with tiny veins that would lead to the “charging point”.


It is said that, millions of years ago, fragments of sun and other planets might have fallen on earth, particularly in South India sub continent. A bigger myth is that the Rishis had traveled to all the planets to collect the metal from each planet. The material from other planets that reached earth thus is used to imprint the corresponding planet on the coin. These are the metals used to mint the Lebbo coins.

Mr. Keerthi Immanuel, a numismatist said, “The metal combined in these coins can be used to control extreme heat power. For example, it can be used to control the heat that is released during the rocket launch.” He further continued that these coins and metals are used in NASA and it has the capacity to drain the charge of a battery in three seconds by placing it at three centimetres close to each other.

The powers of these coins are said to extend even further than just scientific reactions. The more “magical” powers of the coins can be activated by charging the coin on the three pin points, each having different functions. After charging the coin with MRC 87 chemicals, a magnetic attraction of carbohydrate contents is generated on the coin. The coins reportedly can stop a bus when carried in it by stopping the ignition, bend candle flames towards it, attract rice to it, and act as a circuit to turn on light bulbs.

Many people strongly believe in the existence and power of Lebbo coins, do you?

Pompeii and the Coins That Survived Vesuvius


“The coins archaeologists find,” writes Emma Watts-Plumpkin in the March 2004 edition of World Archaeology, “are those that have been lost or purposely hoarded away. The Pompeii collection is quite different from coins found elsewhere.” Pompeii has fascinated the world since it was uncovered in the late 1700s, and the coins found in the ruins are no exception.


The story of Pompeii and its sister city, Herculaneum, are known. In August of 79 CE, Mount Vesuvius exploded violently (as it had done before, wiping out a much earlier Roman settlement), burying both cities in ash, pumice, and lava. While many inhabitants escaped, those who waited too long were trapped in the cities. In many cases, the bodies were covered in fine ash, producing the famous molds which reveal extraordinary details of the victims.




Many inhabitants tried to take their valuables with them. Wealthy families and individuals have been found with jewelry, statues, bags of coins, and more. Even the underclasses and slaves took the coins they had, usually bronzes and coppers. A fused mass of coins was found at the edge of the ancient beach in Herculaneum; many residents fled there in hopes of boarding boats to escape, but were incinerated when the first of many pyroclastic flows (12 surges in total, by the time the eruption calmed) raced down the mountain. Over the course of hours, 75 feet of rock and ash covered the city, freezing it in time.


800px-View_of_vesuvius_over_the_ruins_of_pompeiiAfter the eruption, some residents did return to try to salvage what they could. Emperor Titus declared Pompeii an “emergency zone,” and even sent funds for rebuilding. But too much had been buried, and within a few decades, both towns were gone from local maps. Statius, a Roman poet, wrote “When this wasteland regains its green, will men believe that cities and peoples lie beneath?” A few centuries later, new farms and vineyards had been planted in the fertile volcanic soil over the city.


In 2016, four skeletons were found in the ruins of a shop near Pompeii’s Herculaneum gate. While the site had been looted, several gold coins were recovered. It’s likely that other coins were initially present, and were taken by the looters who tunneled in.


Approximately 1500 coins have been recovered from an insula (a Roman city block) by a research team from the University of Bradford. The insula contained two large houses, as well as shops and even bars. The coins studied by the Bradford team are unusual in that they show coins in circulation up to the moment of catastrophe, not buried with the dead, hidden in a hoard, or otherwise intentionally collected. As such, most of them show extensive wear, as they were in circulation up until the very moment of disaster.


mapThe Pompeii copper coins show a strong local economy, as the coins are mostly crude copies of Massalian (modern day Marseille) and Ebusian (modern day Ibiza) coins. Very few of the coins come from Rome itself, though a few early Imperial Quadrantes have been found, with more expected to appear as the mass of coins is separated. The pseudo-coins, as they are known, seem to have been locally made and circulated mostly around the Naples Bay area. No coin-minting equipment has yet been found in Pompeii or Herculaneum, but such a find may turn up in future excavations, or simply have been damaged beyond recognition. Watts-Plumpkin writes, “In all likelihood, these ‘pseudo’ coins were just for use in the local economy. The fact that so many have been found bears out the degree to which the people of Pompeii were involved in local trading. The large numbers of local coins also suggests that the Pompeiians may have been using a largely monetised economy rather than other forms of barter. That far fewer coins come from further afield, for example actually from Ibiza or Marseilles, suggests that the people of Pompeii were not engaged in very much monetised longer-distant trade.”


At last date, about 500 of the 1500 coins separated have been identified. The most common is the pseudo-Ebusus design, with a crude image of the Egyptian dwarf god Bes on both sides. These coins are 12-16mm across. Another 45 copper-alloy coins bear the image of Janus, the two-faced Roman god. The reverse of the coin shows the prow of a ship. Some of these coins bear the word “ROMA,” and were made during the Republic. Many of these are found halved, as cutting coins has been an efficient way to make change when softer metals are used.




About 55 of the coins are Massalian in style, though only a few actually come from Massalia itself. Most are the local copies, with a bust of Apollo on the obverse and a bull on the reverse. The best date for these coins is the first century BC; they were in circulation as long as the coin weighed enough to be legal tender.
As evidenced by its coins, gathered up as treasures in the hands of those fleeing the city or left behind in scattered masses, Pompeii was a busy town, much like any other. But its coins still tell the story of daily life in the obliterated city, and there is still so much more to learn.


[Featured image credit of The British Museum, used under fair use.]

Minting A Coin to Prove A Point


What lengths would you go to to prove a point? One early American minter set up his own press and struck his own coins, just to demonstrate that he could. This created one of the rarest coins in United States history.


351105686_bb197d355e_oBefore the creation of the United States Mint and the coinage of American money, John Harper helped created copper coins for the state of New Jersey. While his business partner, Albion Cox, was in charge of the mint, Harper worked with the mechanical processes, and struck the actual coins. After the job ended in 1788,. Harper became a businessman in Trenton, though he sold some of the coin-making equipment to the newly-established United States Mint in 1792. In fact, Harper owned the Philadelphia building that was the first temporary home to the Mint, and where the first silver coinage of the United States was struck.


Harper’s original partner, Albion Cox, returned from England to become the first assayer of the Mint. The Mint began to strike copper coins in 1793, but the public was unhappy with the quality of the coins. So intense was the outcry that Congress appointed a special committee to see what had happened and what could be done to correct the problems. Cox suggested that the committee approach Harper, given his expertise in copper coinage.



The head of the committee, Elias Boudinot, met with Harper and was impressed with his knowledge. However, when Harper met with the full committee, he was left with the impression that they did not take him seriously. He created his own minting machinery from repurposed saw-making machines, and even cut his own dies. He rolled out copper and punched out coin blanks, then invited the committee to visit him again. When the committee arrived, he proceeded to strike coins and distribute them to those present. It was unanimously agreed that Harper did, in fact, know what he was talking about when it came to minting copper coins.


Those handfuls of Harper-struck coins are now known as Jefferson Head cents, due to the resemblance between the historic figure and the Liberty face on the obverse of the coin. It is one of the rarest coins in American history; only about 25 of the coins struck by Harper himself exist; fewer still remain of the coins made by the Mint, using Harper’s dies.

The Sense behind the Cent

The American Revolutionary war was officially ended by Congress on April 11, 1783. It is estimated that America had around 3 Million people in it at the time, all from various European countries.  All these people brought with them the culture and tradition from their native lands and the great melting pot was born.  Along with ideas and traditions came various units of trade.  If you could pop back to this time in American history, you would find coins from all over the world being used for trade.  Each coin had its own value, look and weight.  Imagine the confusion this would cause.  It was soon clear that this country needed its own unit of trade, one that was uniform and would be recognized by anyone.  And so the penny was born.

Designed by Benjamin Franklin, the first penny was called the fugio cent.  It was privately minted from 1787 to 1793 and made solely of copper.  The obverse featured the sun shining down on a sundial with the caption “fugio” (I fly or flee) on one side.  The bottom says “Mind your business”.  The reverse shows 13 interlocking rings meant to represent each of the 13 colonies with the words “we are one” in the center.


From here, a series of what we now call large cents were produced from 1793 to 1856.  Here is a list of the different large cent varieties they made:

Flowing Hair Cent (1793)

Liberty Cap Cent (1793-1797)

Draped Bust Cent (1796-1808)

Classic Head Cent (1808-1814)

Coronet Cent (1816-1857)

Matron Head Cent (1816-1839)

Braided Hair Cent (1839-1857)

No pennies were made in 1815 because of the war of 1812 and the shortage of copper that resulted.

By the mid 1800’s, these large cents were quickly becoming unpopular in commerce and expensive to mint.  These coins were large and became heavy to pack around.  Also, due to inflation, the price of copper started rising so that it was now costing more than 1 cent to make a penny. By 1850, pennies were no longer profitable to mint.



In 1856, the flying eagle cent came into circulation (pictured above).  This coin was much smaller than its counterpart and was made of only 88% copper.  The other 12% was nickel, which was a much more affordable metal.  To get these new “small cents”, people could exchange their large cents or other worn foreign silver.  So many flying eagle cents were made that they quickly overwhelmed the system.  They were not considered legal tender and therefore banks and other merchants did not have to accept the coins. Flying eagle cents were only minted for three years.  The eagle design did not strike well and it was replaced by the Indian head Cent (pictured below).

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The Indian head cent was minted from 1859-1909. Most of these coins were minted to pay union soldiers during the Civil War. After the war, in 1864, its composition was changed once again to be 95% copper and 5% zinc.  Also in this year the Coinage act of 1864 was passed.  This act made the one cent coin legal tender and now merchants and banks across the country had to accept them.

In 1909, to commemorate Abraham Lincoln’s 100th birthday, the design on the penny was changed once again.  Commonly known as the wheat cent (pictured below), this coin featured a profile view of Lincoln on the obverse and a pair of wheat ears circling the words “one cent” on the reverse  Lincoln was the first historical figure to be used on a US coin and his picture remains on the penny to this day.

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Although its design has changed many times, the purpose of the cent remains the same. It was not only our first official coin, but it helped shape our nation.  Check out all the different cents we have for sale on Ebay and our website and stay tuned for more about the infamous wheat cent

The 1787 Brasher Doubloon

One of the rarest coins in the world was made when a goldsmith and silversmith was denied a petition to mint his own coins.

A man named Ephraim Brasher wanted to mint his own copper coins, but ran into a roadblock: the State of New York did not want to mint copper coinage.

But Brasher already had skills applicable to creating his own coins, so he set out to making his own. At the time he was already well known for his skills and his hallmark (his initials ‘EB’), which was stamped on his own coins and any coins that he proofed. Brasher had already established his name, to the point that he was nationally recognized.

So, against the wishes of New York, Brasher made his own coins. Perhaps his high status in the numismatic industry made him a little too confident.

So why are Brasher doubloons the rarest in the world? Few were made, and very few survived, and the rarest of the doubloons are the few that were made in 22-carat gold. The coins made in copper were more common, so they don’t sell for as much.

What do these rare coins sell for? In 2005, Heritage Auction sold all three varieties of the doubloons, where the most valuable, the New York Style EB Punch on Wing, sold for $2,990,000. That wasn’t the highest price paid for a Brasher Doubloon, however. A Wall Street investment firm bought a Brasher Doubloon for the whopping price of almost $7.4 million. Now that’s a valuable coin!

Encased Postage Stamps

During the Civil War, a shortage of supplies forced people to take strange measures. The shortage extended to gold, silver and copper, which people hoarded for themselves. And many people did not believe that paper money had actual value.

In response, the government passed a law in 1862 that allowed people to use postage stamps worth less than $5 to pay off debts to the government since these gave evidence of having paid for postage. Usually the stamps were worth 1 to 10 cents, used to make exact change.

But it was immediately clear that fragile postage stamps might be more trouble than they were worth. The questionable lasting nature of paper made stamps difficult to use as currency.

That’s where a man named John Gault comes in. Gault was an inventor and entrepreneur who created a solution to this stamp problem.


Gault proposed a “New Metallic Currency” that held stamps in a less delicate holder. These coin-shaped holders held a familiar coin shape that prevented stamps from being torn, bent or lost. The holder were originally made of silver so they looked more like real coins, but these quickly proved too expensive, so he made the holders out of brass instead.

Gault knew that he could make a profit from his invention. He sold the cases to stores and, in a clever marketing plan, used the back of the holder for advertising. One of the most prevalent advertisers was J.C. Ayer, a medicine business.

The stamp holders only lasted so long. In 1863 the government issued fractional coins that helped with the coin shortage, and stamps were no longer needed. Gault didn’t produce encased postage long after that as there was no demand for the postage anymore.

These encased stamps are quite rare today because most were torn apart to get to the stamp inside. Mint condition cases can sell for up to $4000.

Ancient Roman Coinage

Ancient Roman coins were some of the earliest coins in history. Bronze, copper, gold and silver coins made up Roman coinage.

(Looking for ancient Roman coins? Look no further.)

Because these coins were made of valuable materials like gold and silver, they had intrinsic value.

Around 300 B.C., the Roman Republican government introduced coinage (about three centuries after Greece, an embarrassingly late time) to its Republic. Because coin systems had already been established, Romans knew all about how to use their currency. Rome was a well-established republic at the time.

The coinage included some oddities. This included bronze bars called “stuck bronze” that weighed around 50 oz. with a high iron content.

Bronze bar, 450 B.C.

Bronze bar, 450 B.C. Courtesy of LmK, CC 3.0

Following Greece’s example, Rome created its own circular coins illustrating myths and scenes with gods and goddesses. Greek coins greatly influenced these designs.

When Julius Caesar took over, he issued coins with his profile. These were significant as they were the first coins to feature a living person. They served to spread Caesar’s image through Rome and beyond. Caesar also released coins showing Venus or Aeneas in the attempt to associate himself with divinity. Other emperors went even farther, however; in 192 Commodus ordered coins featuring himself dressed in a lion skin in an imitation of Hercules, proclaiming himself to be an incarnation of the famous hero.

Caesar profile coins continued even after Caesar’s assassination, along with featured gods and goddesses.

Romans put a lot of moral value on the images in their coins. The philosopher Epictetus wrote as a joke: “Whose image does this sestertius carry? Trajan’s? Give it to me. Nero’s? Throw it away, it is unacceptable, it is rotten.” Romans would not really throw away their coins, but the images still certainly meant a lot to them.

There is more to learn in the world of ancient Roman coins, but these are the basics.