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As seen on Game of Thrones the TV series, some gold is melted in a regular campfire.

http://www.youtube.com/watch?v=J74JEloKC3M

Is this physically and chemically possible?

Sklivvz
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    gold melting point according to wiki: 1337.33 K, 1064.18 °C, 1947.52 °F and a quick google puts campfires at 480-1000°C depending on fuel – ratchet freak Aug 20 '11 at 23:04
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    @ratchet A crown would likely be made from a gold alloy, not pure gold. The melting point of the alloy would be different then, though I don't know if it would be low enough. – Mad Scientist Aug 21 '11 at 07:29
  • Define "regular campfire", you know how many different tree's there are to burn. Some wood buns much hotter than others. I call it a bust. – Moab Aug 24 '11 at 02:40
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    @ Moab: I suppose it's something that an answer should address, not the question. If I already knew the subject so deeply I wouldn't need to ask in the first place. –  Aug 24 '11 at 13:46
  • Anecdotaly, I have build a campfire that got hot enough to soften a glass bottle. Mind you, it was fuel with Texas live oak and we had a brisk, steady breeze blowing right between the two big base logs. Poking about on the internet seem to imply a temperature near or above 1000°F, still not really hot enough. – dmckee --- ex-moderator kitten Mar 26 '12 at 20:37
  • The series ended 6 months ago, I've removed the spoiler... – Sklivvz Mar 27 '12 at 20:37
  • @Fabian: The material melted was not a crown, but from other golden medallions or something similar. But these might also be a gold alloy. The usage of the molten gold was for a "crown" of sorts. – Martin Scharrer Mar 27 '12 at 20:48
  • I actually wondered about this myself after seeing this episode. I actually checked if the metal pan used would not melt as well, but figured out that iron melts for later than gold does. – Martin Scharrer Mar 27 '12 at 20:49
  • @MartinScharrer: iron would not melt, but it should be glowing hot, somewhere between bright red and yellow. So should be the gold. vide: http://eandesolutions.com/sellyourgoldplatinum/images/Melting-gold.jpg – vartec Feb 01 '13 at 15:43
  • A eutectic alloy of Gold with Thallium brings the melting point to 268 F which is almost believable. As we see with Dany grabbing the wooden shaft of a spear with a melting iron point with only superficial second degree burns and surviving the burning off of her hair in Daznak's pit without any scalp burns at all GRRM's materials science is somewhere on a level with his genetics. That's OK though –  Feb 01 '13 at 15:09
  • When I saw that episode, I thought that was lead, which could melt at those temperatures. – pfyon Feb 02 '13 at 03:36

1 Answers1

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Gold melts at 1064 °C, however, in jewellery, gold is often alloyed with copper (wiki). Though copper melts at 1084 °C, the alloy has a lower melting point, as you can see from the phase diagram (note that the temperature is in Kelvin, which adds ~271):

Au - Cu phase diagram

If the crown is 18k gold (¾ gold, ¼ copper), which makes an alloy that is harder than gold or copper alone, and gives a nice reddish hue to the gold, then the campfire only needs to be able to produce ~900 °C, which is achievable with the right fuel according to @ratchet freak's research.

Community
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Jonas
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    Indeed. And if there are additional base metals introduced, like say tin, then you can achieve some impressively low melting points if the proportions are just right. Gold-tin has a eutectic point at 300C! http://pruffle.mit.edu/3.00/Lecture_36_web/node1.html – Mark Beadles Jan 04 '13 at 00:16
  • So it is possible chemically? – Mark Nov 07 '13 at 01:18
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    @ChristianMark: Not sure what you mean - alloying tin and gold is done by dissolving blocks of tin in liquid gold, and stirring. No complex chemistry needed. – Jonas Nov 08 '13 at 12:33
  • While a properly built pyre will certainly burn hot enough, the problem is getting the temperature all the way to the smelting pot. Without some insulating walls, i.e. a kiln, the pot will be losing heat too fast to get at the temperature (note: pottery kiln also needs ~900°, can be wood fired with free draft, but needs to be insulated to maintain the heat). – Jan Hudec Apr 18 '19 at 20:46