Hello, I'm Justin Rowland and welcome to the latest attempt to break down the world economy into its constituent chemical elements.

This week, a riveting program on the future of iron, the metal that underpins the modern world.

But if iron and the steel it is used to create is the metal of modernity,

what does the recent unprecedented collapse at its price tell us about all our futures?

Does it herald a great contraction, or will cheap iron ignite a new boom?

And in the very, very, very long run,

will we even need to continue digging this ubiquitous metal out of the ground at all? I'm standing by a vast construction site in the middle of the Indian capital Delhi.

It's in building sites like these, as well as in the bodies of the cars, buses, bikes and auto rickshaws you can hear whizzing past, where most of the world's iron ends up, mainly in the form of steel.

There are sites like this all over Delhi, evidence that the city, indeed the entire country,

is at the beginning of what could become a gigantic building boom.

But what shape will that boom take?

Can history guide us? Because India is entering on a

well-trodden journey. Professor Daniel Bayat-Muller is a materials scientist at the Norwegian

University of Science and Technology. Iron production is very much related to industrialization.

We are in a phase of building up stocks, moving iron from the ground, from the lithosphere,

to build infrastructure, to build buildings, vehicles, trucks and so on, ships,

so into different products that are in use and eventually

reach end of life and become available as crap. So are you kind of saying that we're building

up a historic stock of iron that then can be reused, that in a sense, you know, as countries

industrialized, they may need less and less iron.

That is possible if we are able to keep the iron stock in use. We still lose a lot of the iron at the end of the life.

A lot of industrialized countries had growing iron stock during the industrialization phase, but their

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