

Barns Are Painted Red Because of the Physics of Dying Stars - shovel
http://www.smithsonianmag.com/smart-news/barns-are-painted-red-because-of-the-physics-of-dying-stars-58185724/?no-ist&utm_source=Atlas+Obscura&utm_campaign=53e176b485-Newsletter_02_13_102_12_2015&utm_medium=email&utm_term=0_62ba9246c0-53e176b485-60248965&ct=t(Newsletter_02_13_102_12_2015)&mc_cid=53e176b485&mc_eid=136a77dbbe

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iwwr
Actually, the reason iron is so cheap is because life chemistry and tectonic-
hydrothermal processes have concentrated it. The bulk of the reserves date
back from the Great Oxygenation event from 2-1 bn years ago when the first
photosynthetic life oxidized the iron dissolved in the ocean and precipitated
it at the bottom of the then-ocean. This didn't happen to aluminium, which is
more abundant than iron, to the same extent. Aluminium was only discovered in
the 19th century and only produced economically as a purified metal in the
latter part of that century. Iron itself took some technology to become cheap
and abundant and before the 12th century BC was regarded as a precious metal
(see:
[https://en.wikipedia.org/wiki/Meteoric_iron](https://en.wikipedia.org/wiki/Meteoric_iron)
).

The price of metals does not match their abundance in the Earth's crust and
least of which the Earth as a planet.

~~~
dredmorbius
Aluminum's also bound much more strongly to its oxides. Generally you need
electrical currents to smelt aluminum, which wasn't possible until the 19th
century (with one possible exception, below).

Iron, on the other hand, can be _heat_ smelted, using charcoal or coal. Iron
smelting drove the use of coal as it was consuming so much by way of forests
earlier. Generally, fuelwood (locally available) is more convenient than coal,
only available from specific areas and mines, and which requires transport
over large distances.

Overland transport prior to the 19th century was something avoided if at all
possible, so coaling routes generally involved ships and oceans or rivers.

There's some evidence that a goldsmith in Rome may have found a process for
smelting aluminum:

"One day a goldsmith in Rome was allowed to show the Emperor Tiberius a dinner
plate of a new metal. The plate was very light, and almost as bright as
silver. The goldsmith told the Emperor that he had made the metal from plain
clay." From: [http://www.world-
aluminium.org/history/antiquity.html](http://www.world-
aluminium.org/history/antiquity.html)

Most versions have him being executed by the emperor to prevent the
devaluation of copper and gold.

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dalke
That's a rather tenuous connection. Nearly everything on Earth is due to the
physics of dying stars. Once could also ask why so many houses in Greece are
white and blue, and the answer would also be "because of the physics of dying
stars."

This article focused on iron. The Earth's crust has more oxygen by mass than
iron, but that point was left out.

~~~
pervycreeper
Furthermore, no explanation given for why the described fusion process stops
at 53, and why heavier elements are also present on Earth.

~~~
dredmorbius
Nuclear binding energy:
[http://en.wikipedia.org/wiki/Nuclear_binding_energy](http://en.wikipedia.org/wiki/Nuclear_binding_energy)

Iron is at the top of the binding energy curve, and hence the _bottom_ of the
potential curve. Effectively, it's at the bottom of a hill with hydrogen on
one (very) high side, and uranium and the trans-uranium elements on the other
(less) high side.

------
shawkinaw
Yeah, it's not actually the physics of dying stars, but the physics of the
nucleus and the fact that iron is at the binding energy maximum [1].

[1]
[https://en.wikipedia.org/wiki/Nuclear_binding_energy#Nuclear...](https://en.wikipedia.org/wiki/Nuclear_binding_energy#Nuclear_binding_energy_curve)

~~~
dredmorbius
Other than _very_ small traces of helium, _all_ elements other than hydrogen
are formed in stars. Mostly supernovae.

So if you want to know what stardust looks like, look around you.

