Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A 3K-year-old copper smelting site could be key to understanding origins of iron

phys.org

Post reply on HN
Print view View original

51–60 of 91 posts

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#51

Post by dboreham »

contrarian1234 wrote: post #40
lukan wrote: post #7

Earlier quoted context omitted.

"they just had a theory that copper processing lead to discoveries in iron processing." Is there any theory how it could have been any different? It sounds obvious, that advances in metal working comes from those working with metals and not from carpet makers.

i have zero background in this topic.. but if i were to guess there are >100x more ceramic kilns than there are bronze smelters if some people chucked random ores into ceramic kilns, maybe one would get out some iron slag and then iterate from there theres a great blog series about making iron. https://acoup.blog/2020/09/18/collections-iron-how-did-they-... its easy on paper, but when you get into the details its act…

Having been a kid living in a place that had open fires burning (new houses were under construction and the builders often made fires to get rid of scrap materials), I can say that the desire in the primitive mind to throw random things into a roaring fire to see what happens, is strong.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#52

Post by mrob »

Sharlin wrote: post #49
GreenWatermelon wrote: post #39

Earlier quoted context omitted.

One of the axioms I go by is that people were never stupid. Our ancestors 5000 and 10000 years ago were just as smart , intelligent and curios as we are today. With regards to metals, I have no doubt someone, be it a kid apprentice or a master smelter, experimented with melting different rocks to see what comes out. After all, if you already know that different rocks spew out different metals (copper, tin, etc..) it…

> Then someone will give that mee Iron sword/knife/axe a try , duel a friend, ruin their bronze weapon, and said friend will be like "holy shit I want an iron sword too it's way too good" and bam you got a meme. Iron is not a superior material to bronze, if anything it's inferior. Iron's either soft or brittle, depending on carbon content, neither of them awesome qualities in a tool or a weapon. Also, iron's consider…

One big advantage of iron is that you can forge it. Bronze has to be cast or cold worked (with annealing steps as necessary). You can't forge weld bronze either, so you need to braze/solder parts together. A skilled blacksmith can forge things from iron quickly and with little waste. It's especially important for things like nails and arrowheads that are needed in mass quantities.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#53

Post by pixl97 »

card_zero wrote: post #47
GreenWatermelon wrote: post #39

Earlier quoted context omitted.

One of the axioms I go by is that people were never stupid. Our ancestors 5000 and 10000 years ago were just as smart , intelligent and curios as we are today. With regards to metals, I have no doubt someone, be it a kid apprentice or a master smelter, experimented with melting different rocks to see what comes out. After all, if you already know that different rocks spew out different metals (copper, tin, etc..) it…

Ideas improve over time. So people in the past have worse ideas. This might include fear of change, and some mythological notion of an eternal golden way of life, which you must dutifully maintain by spending a thousand years not inventing pottery, and if anybody dares to try it, beating them up.

The improvement of ideas over time is a rather complex process.

It's multiple things working together. Typically you have to have an excess of calories which leads to free time in at least part of the population. While the 'fear of change' as gods fault is more of a post ad hoc rationalization of the horizon problem. That is any change in behaviors in the good times could lead to death in the hard times. Moving away from what works has risks.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#54

Post by Sharlin »

mrob wrote: post #52
Sharlin wrote: post #49

Earlier quoted context omitted.

> Then someone will give that mee Iron sword/knife/axe a try , duel a friend, ruin their bronze weapon, and said friend will be like "holy shit I want an iron sword too it's way too good" and bam you got a meme. Iron is not a superior material to bronze, if anything it's inferior. Iron's either soft or brittle, depending on carbon content, neither of them awesome qualities in a tool or a weapon. Also, iron's consider…

One big advantage of iron is that you can forge it. Bronze has to be cast or cold worked (with annealing steps as necessary). You can't forge weld bronze either, so you need to braze/solder parts together. A skilled blacksmith can forge things from iron quickly and with little waste. It's especially important for things like nails and arrowheads that are needed in mass quantities.

Good point!

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#55

Post by aidenn0 »

ReptileMan wrote: post #31

Can anyone explain iron - unless it is steel (which was not a common knowledge trough history) it is worse than bronze in every aspect. So what lead to the iron age?

1. Once you know how to make a hot enough furnace, iron is cheaper to make than bronze. Instead of finding copper and tin ore separately, you just need red rocks and a whole lot of trees. Quantity can trump quality.

2. There was steel in use already prior to 1000BC. High Carbon steel was being produced in both Europe and Asia by 400 BC. When people say "the iron age" it includes the usage of steel (which is mostly iron).

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#56

Post by whycome »

OJFord wrote: post #18

Can anyone recommend a book (I'm imagining sort of 'coffee table' style picture book, but not necessarily) on technological advancements through human history, ideally roughly chronologically but more organised around what needed to happen before the next was possible?

James Burke should write the book to accompany his "Connections" tv show.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#57

Post by themotherhucker »

Sharlin wrote: post #49
GreenWatermelon wrote: post #39

Earlier quoted context omitted.

One of the axioms I go by is that people were never stupid. Our ancestors 5000 and 10000 years ago were just as smart , intelligent and curios as we are today. With regards to metals, I have no doubt someone, be it a kid apprentice or a master smelter, experimented with melting different rocks to see what comes out. After all, if you already know that different rocks spew out different metals (copper, tin, etc..) it…

> Then someone will give that mee Iron sword/knife/axe a try , duel a friend, ruin their bronze weapon, and said friend will be like "holy shit I want an iron sword too it's way too good" and bam you got a meme. Iron is not a superior material to bronze, if anything it's inferior. Iron's either soft or brittle, depending on carbon content, neither of them awesome qualities in a tool or a weapon. Also, iron's consider…

Very minor semantic nitpick as a metallurgist, martensitic and austenitic are not terms that distinguish the ductility of the metal, they are ways the atoms organize into crystal structures (which do have an effect on hardness/ductility).

Austenite is one of the high temperature crystal structures of iron, and is not usually seen at room temperature except in certain non-heat-treatable stainless steels, and in highly alloyed steels some small amounts of retained austenite remains that doesn't get the chance to transform due to low cooling rates and suppressed M_f temperatures. Martensite forms by rapidly cooling austenite without giving the atoms the ability to re-organize into their preferred structure (ferrite, pearlite, or cementite depending on the carbon concentration). This transformation actually changes the size of the crystal matrix, which locks in a ton of internal stress as atoms want to move around but can't. All of this internal stress must then be overcome by an external stress to move the atoms around, resulting in a much harder material.

Martensite requires extremely fast cooling rates (on the order of 100s of degrees/second), which is why most carbon steels are quenched to harden them. These cooling rates are only able to be achieved a little ways into the bulk of the material, so you usually end up with a hardened case made of martensite, and a softer more ductile core that is usually pearlite (layers of ferrite [pure iron] and cementite [iron carbide]) that form due to the slower cooling in the core. This is usually actually more desirable than an entirely through hardened piece, as the hard surface can resist wear and indentation, while the soft core increases the ductility and toughness which reduces the risk of fracture.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#58

Post by Sharlin »

themotherhucker wrote: post #57
Sharlin wrote: post #49

Earlier quoted context omitted.

> Then someone will give that mee Iron sword/knife/axe a try , duel a friend, ruin their bronze weapon, and said friend will be like "holy shit I want an iron sword too it's way too good" and bam you got a meme. Iron is not a superior material to bronze, if anything it's inferior. Iron's either soft or brittle, depending on carbon content, neither of them awesome qualities in a tool or a weapon. Also, iron's consider…

Very minor semantic nitpick as a metallurgist, martensitic and austenitic are not terms that distinguish the ductility of the metal, they are ways the atoms organize into crystal structures (which do have an effect on hardness/ductility). Austenite is one of the high temperature crystal structures of iron, and is not usually seen at room temperature except in certain non-heat-treatable stainless steels, and in highly…

Thanks, I was a bit confused by the different allotropes. Interesting that the martensite transform naturally only happens on the surface (which as you say is actually desirable) due to the rapid cooling it requires, I didn't know that. But of course it makes sense that quenching doesn't instantly cool the bulk of the workpiece.

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#59

Post by jandrewrogers »

lightedman wrote: post #46
jandrewrogers wrote: post #3

Earlier quoted context omitted.

Absolutely. As luck would have it, many epithermal mineral deposits have both sparkly hematite and copper ore in the same structure. This is a well-known motif in mineral exploration. They show up in the same geography but are separated into different layers. You can find many papers on the structure of these ore bodies. These are known as supergene deposits[0]. The most important features of these deposits is that t…

"Amazing hematite crystals mixed with copper with strong assay signs of gold underneath." Did you actually assay out anomalous gold concentrations or are you seeing the sulfides and oxides that are associated with gold? If the former, what sort of concentration are you getting?

I have only assayed samples from the iron cap. You would not expect to find much in that part of the formation but it still came in at 1-2g/ton. There is a large area of visually striking bornite[0] that I have not yet been able to properly sample which is roughly the area you would expect the gold to concentrate. It is in the walls of a narrow, deep canyon at high elevation. The region was mined for gold/copper a century ago, so the existence is not surprising.

The location makes access extremely challenging. It requires 3 hours of hiking, assuming you are fit, and borderline technical mountaineering once you get close to the site. The lower parts of the canyon are also under tens of meters of ice most of the year, which creates a separate set of safety issues. When these mountains were prospected in the 1920s, it would have been underneath a deep permanent snow field. I've visited some of the old gold mines in the area for calibration and this deposit appears substantially larger than those.

The discovery was accidental. I was looking for a waterfall I had seen on satellite imagery in the backcountry and came across an enormous chunk of molybdenite[1] while climbing across granite scree. I made several trips to find the source of the molybdenite higher up the mountains, which I never did, but while searching for that I localized a bunch of other beautiful sulfide/oxide mineral specimens to the above canyon. It gives me a great excuse to explore parts of the mountains no one has been into before.

[0] https://en.wikipedia.org/wiki/Bornite

[1] https://en.wikipedia.org/wiki/Molybdenite

Re: A 3K-year-old copper smelting site could be key to understanding origins of iron

#60

Post by vanderZwan »

jonathaneunice wrote: post #50
vanderZwan wrote: post #35

> These discoveries give weight to a long-discussed theory that iron was invented by copper smelters. Not to be flippant but who else could reasonably be expected to have invented it? Or is the implication that there were metalworkers at the time who weren't also copper smelters?

Right? "Early metallurgists found to have been experimenting with the properties of metals and ores, laying the foundation for future advances that would prove economically and technologically important" is not the biggest possible reveal.

To be clear, I'm not dismissing the research, which seems to be more about how they discovered it. I can understand if that was/is an open question, and these possible answers are pretty interesting. I was just wondering if there were competing theories here with reasons to doubt one is more likely than the other.
Post reply on HN