The One Thing Nobody Tells You About The IUD
The copper intrauterine device, or IUD, is one of the most effective methods of contraception. Have a doctor shove a T-shaped copper wire into your uterus and watch as you suddenly prove completely invulnerable to pregnancy! But when it comes to how the copper IUD actually works, without any hormones in it preventing pregnancy, most of us might not have a clue. It turns out that the mechanism that makes copper IUDs so effective is still kind of mysterious but we do know it has to do with copper ions and how they interact with sperm as it enters the body.
But first, a little history: there's a thoroughly debunked story that the idea of the copper IUD originated with Arabian traders putting copper in their camels' uteruses, but it looks as if copper had its real entry into the world of commonly produced contraception in 1969. The Chilean physician Jaime Zipper began to add copper to intra-uterine devices, improving on a design by his colleague Howard Tatum at the Population Council which actually fitted properly into the uterus. Tatum's the one who came up with the idea of the T-shape we see on modern IUDs before that, IUDs were in many coiled shapes, often looking slightly like children's graffiti. Case Western Reserve University's collection of pre-T IUDs will make your uterus contract.
If you're not particularly worried about how the copper IUD works in your body, only that it does work, be reassured: it's got an insanely good success rate. It's one of the most trustworthy contraceptives there is, and as we'll discuss, science indicates that it doesn't raise the risk of being poisoned by copper or damage your fertility in the future. If you are curious, though, and not satisfied by the perfunctory explanations of copper-as-sperm-killer at your gynecologist's office ("copper is toxic to sperm?" why?!), this is the article for you. But be warned, it does include some gory bits, like sperm tails falling off and rogue sperm being absorbed into your own cells. (Not to be read while being starry-eyed about pregnancy, that's all I'm saying.)
So this is the one thing you may not be told about the copper IUD: how copper toxicity actually works. Get ready for a slightly sticky, sperm-deadly ride.
Why Copper Is Massively Bad For Sperm
When it comes to contraception, copper has a bit of a mysterious effect. But the real aim of the copper IUD isn't the cervix, the ovaries, or our eggs: it's the sperm itself. Copper's a massively effective spermicide, and the sperm are killed off before they can fertilize anything and produce a case of the babies. But why is copper so rampantly toxic to sperm in particular without hurting any other parts of the reproductive system?
The IUD works by releasing copper ions, but they aren't going to migrate all over your body: a study of rats in 1972 found that putting copper in one "horn" of the uterus didn't affect the rest of it, indicating that copper isn't planning on escaping your reproductive organs. And it's the ions that cause the real trouble to sperm. A copper IUD's ions create a completely toxic environment to foreign bodies, including sperm that environment prompts sperm phagocytosis, in which the sperm is killed and then "devoured" by other cells.
It's not all about direct attack, though. You'll remember from sexual health class that sperm look like miniature tadpoles, and have to "swim" to try to penetrate an egg. Copper ions seriously inhibit the ability of sperm to move, which is called their "motility". That effect carries all the way up into your fallopian tubes.
One of the most dramatic things copper does? It actually detaches the sperm from its tail. The UN's report on how the copper intra-uterine device works looked at sperm when they're affected by the copper IUD, and a majority of them had separated in half, head from tail. That's one hell of a way to make sure you don't get preggers.
How The Copper IUD Protects You From Pregnancy (Besides Killing Sperm)
It's not just that the copper IUD kills sperm, either. It looks like copper also alters the thickness of cervical mucus, making it harder for sperm to get through, which is how the hormonal IUD works too. But the level of copper in the mucus of the cervix also means that the sperm can't actually penetrate it.
Interestingly, copper IUDs, if inserted up to five days after unprotected sex, can operate as seriously effective emergency contraception, though frankly it's not necessarily the best idea unless you've already got an appointment scheduled.
Is Copper Safe?
You might be worried that a copper device in the body might result in copper toxicity, a nasty condition where copper (which is toxic to humans in large doses) causes all kinds of side effects. But studies have shown that the copper ion levels released by IUDs are actually tiny, and certainly not enough to do anything to human health. In fact, a 1980 study found there was no difference in bodily copper levels between people with copper IUDs and people without them.
Does Copper Affect Future Fertility?
Copper isn't just an effective sperm killer in ladies' bodies. A study of 232 infertile men in Iran found that all of them had high levels of copper in their bodies, meaning that copper might be a serious complicating factor for men's fertility. But it's important to note a few things. One is that there's no evidence that copper IUDs actually act as abortive mechanisms once a fertilized embryo is implanted (which is how a pregnancy starts). They're not going to stop a pregnancy if something slips through a net.
There's also, according to current studies, no sign that having an IUD will affect your future fertility if you decide to have it removed and try to get pregnant a study in China found that nearly 80 percent of women who chose to have a copper IUD removed were able to get pregnant afterwards.
If you've heard that IUDs can cause infertility, that's actually a hangover from an earlier, now-banned form of intra-uterine device, the Dalkon Shield, that caused all kinds of havoc in the 1970s because it had a flaw that allowed bacteria to be introduced into the uterus. Don't worry modern IUDs, including copper ones, don't have this flaw and don't have the same risks.
In fact, since copper IUDs are non-hormonal, you could theoretically get pregnant the same day you get it removed. And if that still sounds like a nightmare, the good news is, the copper IUD lasts up to 10 years.
Want more women's health coverage? Check out Bustle's new podcast, Honestly Though, which tackles all the questions you're afraid to ask.
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Why isn’t it widespread in hospitals?Hand gel is not as effective as copper. Shutterstock
So if copper is so great, you may be wondering, why don’t hospitals have more copper fittings and fixtures? Well, while some hospitals are installing copper fittings, many others are still not aware of its properties. When doctors are asked to name an antimicrobial metal used in healthcare, the most common reply is silver – but little do they know that silver does not work as an antimicrobial surface when dry – moisture needs to be present and so silver would have an antibacterial effect, like copper does, on hand rails and surfaces which have frequent hand contact.
Cost could also be a factor. Hospitals may perceive hand-gel dispensers as cheaper options, despite the fact that these gels do not all kill all microbes – including the norovirus. Yet an independent study by University of York’s Health Economics Consortium has shown that, taking the reduced costs of shorter patient stay and treatment into consideration, the payback time for installing copper fittings is only two months.
Making and installing copper fittings is no more expensive than using materials such as stainless steel which, ironically, is considered easier to keep clean due to its bright surface. However, we know that these are covered in microscopic indentations and scratches from regular wear and tear, leaving valleys for superbugs and viruses to reside in and escape cleaning procedures. Cleaning happens at best once a day, while copper works 24/7 – so it is surely an important adjunct in the fight to keep the built environment clean.
The importance of installing copper fittings has been recognised in France where various hospitals are now installing copper. Finally, at least some nations of the world are waking up to this simple approach to control infection, let’s hope others are quick to follow suit.
Are copper masks effective against the coronavirus?
Schmidt told TODAY that if reputable retailers start making these types of masks, it could be a "game changer." He added, "If we begin to incorporate copper masks into our strategy . we may be able to short-circuit a second wave that's coming."
One 2010 study in the scientific journal PLOS One that looked at copper masks to reduce spread of influenza seems to support this idea.
"(Copper) masks may significantly reduce the risk of hand or environmental contamination, and thereby subsequent infection, due to improper handling and disposal of the masks," it concluded. (Note: The authors of the study worked at Cupron, a company that makes copper masks, and the company funded the work.)
But Dr. William Schaffner, medical director of the National Foundation for Infectious Disease in Bethesda, Maryland, is "dubious" that copper masks are better than regular ones.
Using copper to prevent the spread of respiratory viruses
New research from the University of Southampton has found that copper can effectively help to prevent the spread of respiratory viruses, which are linked to severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).
Animal coronaviruses that 'host jump' to humans, such as SARS and MERS, result in severe infections with high mortality. The Southampton researchers found that a closely-related human coronavirus -- 229E -- can remain infectious on common surface materials for several days, but is rapidly destroyed on copper.
A newly-published paper in mBio -- a journal of the American Society for Microbiology -- reports that human coronavirus 229E, which produces a range of respiratory symptoms from the common cold to more lethal outcomes such as pneumonia, can survive on surface materials including ceramic tiles, glass, rubber and stainless steel for at least five days. While human-to-human transmission is important, infections can be contracted by touching surfaces contaminated by respiratory droplets from infected individuals, or hand touching, leading to a wider and more rapid spread
On copper, and a range of copper alloys -- collectively termed 'antimicrobial copper' -- the coronavirus was rapidly inactivated (within a few minutes, for simulated fingertip contamination). Exposure to copper destroyed the virus completely and irreversibly, leading the researchers to conclude that antimicrobial copper surfaces could be employed in communal areas and at any mass gatherings to help reduce the spread of respiratory viruses and protect public health.
Lead researcher Dr Sarah Warnes said: "Transmission of infectious diseases via contaminated surfaces is far more important than was originally thought, and this includes viruses that cause respiratory infections. This is especially important when the infectious dose is low and just a few virus particles can initiate an infection.
"Human coronavirus, which also has ancestral links with bat-like viruses responsible for SARS and MERS, was found to be permanently and rapidly deactivated upon contact with copper. What's more, the viral genome and structure of the viral particles were destroyed, so nothing remained that could pass on an infection. With the lack of antiviral treatments, copper offers a measure that can help reduce the risk of these infections spreading."
Speaking on the importance of the study, Professor Bill Keevil, co-author and Chair in Environmental Healthcare at the University of Southampton, said: "Respiratory viruses are responsible for more deaths, globally, than any other infectious agent. The evolution of new respiratory viruses, and the re-emergence of historic virulent strains, poses a significant threat to human health.
"The rapid inactivation and irreversible destruction of the virus observed on copper and copper alloy surfaces suggests that the incorporation of copper alloy surfaces -- in conjunction with effective cleaning regimes and good clinical practice -- could help control transmission of these viruses."
Previous research by Professor Keevil and Dr Warnes has proved copper's efficacy against norovirus, influenza and hospital superbugs, such as MRSA and Klebsiella, plus stopping the transfer of antibiotic resistance genes to other bacteria to create new superbugs.
How to Sell Copper
This article was co-authored by Michael R. Lewis. Michael R. Lewis is a retired corporate executive, entrepreneur, and investment advisor in Texas. He has over 40 years of experience in business and finance, including as a Vice President for Blue Cross Blue Shield of Texas. He has a BBA in Industrial Management from the University of Texas at Austin.
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Selling copper tends to be more lucrative than selling other kinds of scrap metal. If you have access to scrap copper at construction or renovation sites or at electronics or appliance repair shops, consider selling the copper for a profit. Know how to prepare the copper for sale to get the best price. However, be aware that businesses and scrap yards are now working closely with the government to catch copper thieves. Verify that you can legally remove copper from any site, and understand the consequences if you are caught stealing.
Mummified by accident in copper masks almost 1,000 years ago: but who were they?
Academics restart work to unlock secrets of mystery medieval civilization with links to Persia on edge of the Siberian Arctic.
A red-haired man was found, protected from chest to foot by copper plating. Picture: Kate Baklitskaya, Go East
The 34 shallow graves excavated by archeologists at Zeleniy Yar throw up many more questions than answers. But one thing seems clear: this remote spot, 29 km shy of the Arctic Circle, was a trading crossroads of some importance around one millennium ago.
The medieval necropolis include 11 bodies with shattered or missing skulls, and smashed skeletons. Five mummies were found to be shrouded in copper, while also elaborately covered in reindeer, beaver, wolverine or bear fur. Among the graves is just one female, a child, her face masked by copper plates. There are no adult women.
Nearby were found three copper masked infant mummies - all males. They were bound in four or five copper hoops, several centimeters wide.
Similarly, a red-haired man was found, protected from chest to foot by copper plating. In his resting place, was an iron hatchet, furs, and a head buckle made of bronze depicting a bear.
The feet of the deceased are all pointing towards the Gorny Poluy River, a fact which is seen as having religious significance. The burial rituals are unknown to experts.
Five mummies were found shrouded in copper, while also elaborately covered in reindeer, beaver, wolverine or bear fur. Pictures: The SIberian Times, Natalya Fyodorova
Artifacts included bronze bowls originating in Persia, some 3,700 miles to the south-west, dating from the tenth or eleventh centuries. One of the burials dates to 1282, according to a study of tree rings, while others are believed to be older.
The researchers found by one of the adult mummies an iron combat knife, silver medallion and a bronze bird figurine. These are understood to date from the seventh to the ninth centuries.
Unlike other burial sites in Siberia, for example in the permafrost of the Altai Mountains, or those of the Egyptian pharaohs, the purpose did not seem to be to mummify the remains, hence the claim that their preservation until modern times was an accident.
The soil in this spot is sandy and not permanently frozen.A combination of the use of copper, which prevented oxidation, and a sinking of the temperature in the 14th century, is behind the good condition of the remains today.
Belt buckle, fragments of the belt, bracelet and silver decorations researchers found inside the burials. Pictures: Natalya Fyodorova
Natalia Fyodorova, of the Ural branch of the Russian Academy of Sciences, said: 'Nowhere in the world are there so many mummified remains found outside the permafrost or the marshes.
'It is a unique archaeological site. We are pioneers in everything from taking away the object of sandy soil (which has not been done previously) and ending with the possibility of further research.'
In 2002, archeologists were forced to halt work at the site due to objections by locals on the Yamal peninsula, a land of reindeer and energy riches known to locals as 'the end of the earth'.
The experts were disturbing the souls of their ancestors, they feared. However, work is underway again, including a genetic study of the remains headed by Alexander Pilipenko, research fellow of Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences.
'Nowhere in the world are there so many mummified remains found outside the permafrost or the marshes'. Pictures: Kate Baklitskaya, Go East
Fyodorova suggests that the smashing of the skulls may have been done soon after death 'to render protection from mysterious spells believed to emanate from the deceased'.
Copper Alloy Female Mask - History
C hoctaw beadwork artist Marcus Amerman created as a beadwork magazine cover the entire portrait of 19th century Crow leader, Medicine Crow, magazine title lettering and all, for the Fall, 1992, issue of Native Peoples magazine. His beadwork portrait was photographed for the cover. Amerman has mastered shading with bands and areas of beads, and has essentially created a new art form.
E veryone has seen Native American watchbands, cigarette lighter-holders, belts, purses and other small items.
S ince the 1960's, this "modern" beadwork has been imitated in oriental factories and imported very cheaply. It competes with high-quality beadwork of native craftspeople. A U.S. General Accounting Office study done in the mid-80's indicated that native craftspeople have lost tens of millions of dollars in potential sales (over an 8-year period) to such fakes. Since the passage of the 1990 Native American Arts and Crafts Act, [18 USC Sec. 1159, 1993] it is a federal felony to offer imitations as the product of Indian craftspeople.
B eads are a many-faceted part of native history in north America and Canada. The 6-strand turquoise necklace at the left was made by the Joe Garcia family, Santo Domingo Pueblo, New Mexico, in 1984. It's a duplicate of one their daughter dances in. The beads are so carefully size-graduated there seems no break between them. Pink spondylus shell (whose use in ornament is very ancient and shows that there were trade routes from the Pacific all over North America) covers the ends of the strands. The necklace is similar to some that were made thousands of years ago.
M aking beads is an old craft. Bone, stone (turquoise and other semi-precious stones) and shell beads are still made the ancient way, little affected by modern technology. Sea shells, the commonest material for handmade beads, have been important native regional trade items for thousands of years.
B eads were carved and shaped of animal horn, turtle shell, and deer hooves, often for dangling dance tinklers or rattlers. Animal teeth and claws were bored and strung. Bear or wolf-claw necklaces were proof of a hunter's powers. Wooden beads, sometimes dyed, were carved and drilled. Hard seeds were steamed to soften them for awl piercing and stringing. Small animal bones were polished and shaped into taperedcylinders (called hairpipe bone) for neck chokers and large dance regalia breastplates. Softened, flattened dyed porcupine quills -- used here for this Tsistsistas (Northern Cheyenne) 19th-century horse mask -- were used before trade seed beads became common. Quillwork is seeing a revival today.
C heyenne women's qulling societies undertook quillwork as a sacred task. A woman had to be sponsored and tutored for membership. The objective of these societies was technical perfction in the art. Sacred quillwork in many areas was undertaken to fulfill a vow as a form of prayer for someone. The process of making it was sacred, but the finished piece -- to be worn or used by someone -- was not considered sacred. The product was of secondary importance to the process of creation, according to John C. Ewers, of the Smithsonian Institution. The focus was on the vow, the thoughts and prayers and the work, not on the thing -- very different from Western society, which prizes only things and ignores the process of creation.
F resh-water clamshells were used for the Haudenosee (Iroquois League) purple and white wampum chains that recorded treaties, sacred ceremonies, and songs before and after the coming of the Europeans. These chains or belts were treated with great respect, and highly valued by their keepers. Agreements were generally recorded this way. The result was that Europeans believed wampum belts or chains were money, and the word "wampum" even became a sort of slang for money. Actually, they were more like important original documents.
A nimal sinew split fine was the commonest material used to string beads and to attach beads to hide garments, although occasionally strong twined plant fibers (such as nettle) or hide thongs were used.
T he only ancient type of bead still made in quantity today by native people is the heishii, made by Navajos and some pueblo people. The ancient techniques are still used. Shells (especially olive shell), slices of turquoise, and occasionally other semi-precious stones are broken into small pieces. A hand-pump drill makes a small hole through each piece, drilling from both sides if it is thick. The heishii are then strung. The string is rolled on a piece of fine sandstone until they are smoothed into uniform cylinders around the string-hole. The smaller the bead, the more work involved, so the more expensive they are. Heishii necklaces are always many - stranded, sometimes all of a kind, but turquoise with shell heishii are also common.
A nimals and other figures are carved from flat pieces of turquoise or shell. These are drilled and strung between groups of "rocky" or shaped turquoise, silver, or heishii shell beads to make "story" necklaces, where the storyteller can show children each character as she tells the story. Some say women first got the idea for story necklaces from the rosary beads of Catholic priests. Most purchased "story- type" necklaces actually tell no story, but mothers, older sisters, grandmas and teachers make one up to fit the beads. (White traders have given storyteller necklaces the unfortunate name of "fetish" suggesting both some kind of cult and psychological obsession.)
B eads are important in archaeological studies of pre-European history. They survive thousands of years well. Seashell beads are important because ancient shell beads are found thousands of miles from seacoasts, indicating trade contacts among ancient peoples. How beads are made helps show the level of technology of the ancient people who made them. Since beads are not tools, their use and production means a tribe had enough food and shelter to spend time or trade goods on ornaments unnecessary for physical survival. This means a more complex culture.
E uropeans made other types of beads available. Glass (made in Venice, Italy), ceramic, and cast metal beads (silver, brass, and German silver--an alloy of nickel, copper and zinc) were trade items used from the 16th century on.
W hen Indian women get together to do beadwork, someone often jokes, "My nephew just came back from New York City. He says the shape it's in today, that's one land deal we got the better of." This refers to the alleged "sale" of Manhattan Island to Dutch colonists around 1620 for $25 worth of beads by someone from the Wappinger Confederacy. (Most likely they thought the newcomers were giving them guest-gifts.)
T rade beads facilitated early European penetration of the northern Woodland culture area. They were a useful item for "coureurs de bois" (woods-runners) who carried light trade goods in backpacks on forest trails and in canoes on long early northern woodland travels, pursuing beaver pelts during the 17th and 18th centuries. Lightweight, easy to pack, undamaged by water, immediately desirable to most tribes who never saw them before, beads were among the "gift trinkets" carried by most explorers and expeditions to help in making contact with tribes newly met.
W ith the exception of early 20th-century ethnographer Frances Densmore, anthropologists (almost all male) have ignored native use of "trade" beads, in their studies of native subsistence, craft and ornament. Native women were inspired to invent beadwork techniques unknown to Europeans, as well as beautiful and sometimes spiritually or historically-inspired culturally unique designs.
T wo types of trade beads were immediately popular (and are still used by native craftspeople). The big ceramic pony beads are about a quarter to half an inch in diameter, with large holes for thongs. These are used on bone chokers and dance breastplates, as well as danglers from medallion necklaces. Red, black, and turquoise-color are the most popular. A few are still made of brass. Their name comes from the fact that these beads are well suited to thong-strung decorations on pony reins and other horse gear. Shown here is a hairpipe bone choker with red and brass pony beads and a large abalone-shell button.
T he most widely-used beads today-- eagerly accepted by native women from their first introduction--are tiny seed beads. Their use supplanted the more difficult, time- consuming (and not so flexible) porcupine quillwork.
M anido-min-esag ("Little spirit seeds, gift of the Manido" the Anishnaabemowin name for seed beads) was what Anishnabe (Ojibwe, Odawah, Pottawotomi) women named seed beads. The need to have good feelings when one is beading continues this early reaction: that these little things were a gift of beauty from the spirits, handed over by the white man as an intermediary of some sort.
A lmost as soon as seed beads were available, native women invented two techniques for using them: loom beading and applique embroidery. Those two techniques are still in use today. Loom-beading and a form of single-needle weaving (peyote beading) are not adaptations of techniques known to European or other cultures they are native inventions. Read about Modern seed-beading techniques now or later.
F ine quality seed glass beads are made only in Czechoslovakia. They were unavailable after World War II until the mid-'60's. Larger, coarser, unsatisfactory beads were used, and older objects were "de-beaded" to make new regalia for relatives, until Czech beads again became available. Very fine, long needles are required, and fine nylon thread is used today for all seed beading.
B eadwork today uses all the traditional techniques. Most of the finest beadwork is still done only for relatives and gift giveaways. A lot of work goes into a large piece. To fully bead the yoke and upper sleeves of a fine Plains buckskin dance dress takes 20 pounds of number 12 seed beads and about a year of work. As much time is required to prepare a set of Wood- land-style mens' dance regalia: beaded leggings, cuffs, vest, breechclout-apron, strips and medallions to attach to head roach, bustle, and dance-sticks.
O f course this isn't "continuous" or factory-style work, it's done after regular jobs and housework. Still, such "large" projects are generally made only for relatives, or commissioned by dancers from well-known beadworkers. Items for sale are smaller, take less time, and provide a little extra income when sold in Indian Center craft shops or at powwows.
A s a 1990 project whose actual purpose was to teach the use of a complex professional computer design program, North Carolina Cherokee and Choctaw college students learned to use AutoCad for beadwork designing. Others have tried it with simpler, less expensive computer programs. Here's
Navajo crafts and LOGO programming-- Monument Valley HS, Dinè Bi K'ah Reservation, Utah. Button here is some student computer design work.
C omputer beadwork design is like Woodland designing by moving around birchbark cutouts, with the addition that colors can be explored, outline shapes easily changed. The designs provide a clear idea of what a project--which might take years to bead--will eventually look like.
B eads weave through native history from tens of thousands of years ago to tomorrow's computer design technology. But there is another aspect besides techniques and designs, craft and ornament.
B eaded items for religious purposes are either made personally (medicine pouch, Pipe bag), or given by relatives, not bought or sold. Beadwork on such items often reminds the owner of a personal vision or sign or the meaning of a personal name, it is not only to make them beautiful. However, making sacred objects beautiful, especially by taking a lot of time and care, shows honor and respect to the spiritual powers, not only through words and feelings, but through artistry and work. This reality -- the work done as itself a prayer or vow -- underlies and strengthens ceremonial activities.
Webmistress --Paula Giese. Text and graphics copyright 1995, 1996.
CREDITS:Daisy and bone choker are drawn by me. Cover photo from Native Peoples Magazine , Fall, 1992. Storyteller necklace was sold by a New Mexico company called Native USA sveral years ago. The Garcia family turquoise necklace was photographed for the Coe collection catalog, Traditions Lost and Found a travelling show for several years. It is unfortunately now out of print. Subscriptions of Native Peoples Magazine are highly recommended for minority studies from grades 6+. The interesting articles, always accompanied by beautiful photos and artwork, are made even handier for teachers to use in their classrooms by study guides for each issue prepared by the magazine's staff. You can visit their site for some samples.
In many regions, copper-arsenic alloys, of superior properties to copper in both cast and wrought form, were produced in the next period. This may have been accidental at first, owing to the similarity in colour and flame colour between the bright green copper carbonate mineral malachite and the weathered products of such copper-arsenic sulfide minerals as enargite, and it may have been followed later by the purposeful selection of arsenic compounds based on their garlic odour when heated.
Arsenic contents varied from 1 to 7 percent, with up to 3 percent tin. Essentially arsenic-free copper alloys with higher tin content—in other words, true bronze—seem to have appeared between 3000 and 2500 bce , beginning in the Tigris-Euphrates delta. The discovery of the value of tin may have occurred through the use of stannite, a mixed sulfide of copper, iron, and tin, although this mineral is not as widely available as the principal tin mineral, cassiterite, which must have been the eventual source of the metal. Cassiterite is strikingly dense and occurs as pebbles in alluvial deposits together with arsenopyrite and gold it also occurs to a degree in the iron oxide gossans mentioned above.
While there may have been some independent development of bronze in varying localities, it is most likely that the bronze culture spread through trade and the migration of peoples from the Middle East to Egypt, Europe, and possibly China. In many civilizations the production of copper, arsenical copper, and tin bronze continued together for some time. The eventual disappearance of copper-arsenic alloys is difficult to explain. Production may have been based on minerals that were not widely available and became scarce, but the relative scarcity of tin minerals did not prevent a substantial trade in that metal over considerable distances. It may be that tin bronzes were eventually preferred owing to the chance of contracting arsenic poisoning from fumes produced by the oxidation of arsenic-containing minerals.
As the weathered copper ores in given localities were worked out, the harder sulfide ores beneath were mined and smelted. The minerals involved, such as chalcopyrite, a copper-iron sulfide, needed an oxidizing roast to remove sulfur as sulfur dioxide and yield copper oxide. This not only required greater metallurgical skill but also oxidized the intimately associated iron, which, combined with the use of iron oxide fluxes and the stronger reducing conditions produced by improved smelting furnaces, led to higher iron contents in the bronze.
It is not possible to mark a sharp division between the Bronze Age and the Iron Age. Small pieces of iron would have been produced in copper smelting furnaces as iron oxide fluxes and iron-bearing copper sulfide ores were used. In addition, higher furnace temperatures would have created more strongly reducing conditions (that is to say, a higher carbon monoxide content in the furnace gases). An early piece of iron from a trackway in the province of Drenthe, Netherlands, has been dated to 1350 bce , a date normally taken as the Middle Bronze Age for this area. In Anatolia, on the other hand, iron was in use as early as 2000 bce . There are also occasional references to iron in even earlier periods, but this material was of meteoric origin.
Once a relationship had been established between the new metal found in copper smelts and the ore added as flux, the operation of furnaces for the production of iron alone naturally followed. Certainly, by 1400 bce in Anatolia, iron was assuming considerable importance, and by 1200–1000 bce it was being fashioned on quite a large scale into weapons, initially dagger blades. For this reason, 1200 bce has been taken as the beginning of the Iron Age. Evidence from excavations indicates that the art of iron making originated in the mountainous country to the south of the Black Sea, an area dominated by the Hittites. Later the art apparently spread to the Philistines, for crude furnaces dating from 1200 bce have been unearthed at Gerar, together with a number of iron objects.
Smelting of iron oxide with charcoal demanded a high temperature, and, since the melting temperature of iron at 1,540 °C (2,800 °F) was not attainable then, the product was merely a spongy mass of pasty globules of metal intermingled with a semiliquid slag. This product, later known as bloom, was hardly usable as it stood, but repeated reheating and hot hammering eliminated much of the slag, creating wrought iron, a much better product.
The properties of iron are much affected by the presence of small amounts of carbon, with large increases in strength associated with contents of less than 0.5 percent. At the temperatures then attainable—about 1,200 °C (2,200 °F)—reduction by charcoal produced an almost pure iron, which was soft and of limited use for weapons and tools, but when the ratio of fuel to ore was increased and furnace drafting improved with the invention of better bellows, more carbon was absorbed by the iron. This resulted in blooms and iron products with a range of carbon contents, making it difficult to determine the period in which iron may have been purposely strengthened by carburizing, or reheating the metal in contact with excess charcoal.
Carbon-containing iron had the further great advantage that, unlike bronze and carbon-free iron, it could be made still harder by quenching—i.e., rapid cooling by immersion in water. There is no evidence for the use of this hardening process during the early Iron Age, so that it must have been either unknown then or not considered advantageous, in that quenching renders iron very brittle and has to be followed by tempering, or reheating at a lower temperature, to restore toughness. What seems to have been established early on was a practice of repeated cold forging and annealing at 600–700 °C (1,100–1,300 °F), a temperature naturally achieved in a simple fire. This practice is common in parts of Africa even today.
By 1000 bce iron was beginning to be known in central Europe. Its use spread slowly westward. Iron making was fairly widespread in Great Britain at the time of the Roman invasion in 55 bce . In Asia iron was also known in ancient times, in China by about 700 bce .