Rust Miracle in the Quran
Some Islamic apologists claim that the Quranic verse 18:96 talks about rust.
The verse doesn't mention rust at all.
Apologists first share scientific information about rust and then they quote a Quranic verse which doesn't mention rust at all:
If iron is exposed to oxygen and water it will eventually convert to rust and disintegrate.
Rust is an iron oxide, a usually red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, and form under different circumstances. Rust consists of hydrated iron(III) oxides Fe2O3.nH2O and iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3). Prevention Coatings and painting Rust formation can be controlled with coatings, such as paint, lacquer, varnish, or wax tapes that isolate the iron from the environment. Wikipedia, Rust, 2019
To prevent rust you have to block the oxygen or water. One of the used methods is to coat the iron. This was known recently; however this was portrayed in the Quran 1400 years before it was discovered. In the story of Thu-Al-Karnain he poured tar over the iron.
[Quran 18:96] "Bring me blocks of iron." So that, when he split it equally between the two shells, he said, "Blow." And having turned it into a fire, he said, "Bring me tar to pour over it."
He coated the iron with tar. Today we know why; tar prevents oxygen and water from reaching the iron, thus preventing rust.
How could an illiterate man who lived 1400 years ago have known how to prevent rust?
Dhul Qurnayn, after he found the place where the Sun sets into a muddy spring, and after he found the place where the Sun rises, he then found people who complained about tribes called "Gog and Magog", so he built a wall between them and the rest of the world:
18:92 Then he followed a way
18:93 Until, when he reached [a pass] between two mountains, he found beside them a people who could hardly understand [his] speech.
18:94 They said, "O Dhul-Qarnayn, indeed Gog and Magog are [great] corrupters in the land. So may we assign for you an expenditure that you might make between us and them a barrier?"
18:95 He said, "That in which my Lord has established me is better [than what you offer], but assist me with strength; I will make between you and them a dam.
18:96 Bring me sheets of iron" - until, when he had leveled [them] between the two mountain walls, he said, "Blow [with bellows]," until when he had made it [like] fire, he said, "Bring me, that I may pour over it molten copper."
18:97 So Gog and Magog were unable to pass over it, nor were they able [to effect] in it any penetration.
The verse 18:96 doesn't mention rust at all. Tafsir al-Jalalayn explains the verse like this:
Bring me ingots of iron!’ namely pieces thereof as large as the blocks of stone to be used in the construction; he used these ingots in his construction placing between them firewood and coal. Until when he had levelled up the gap between the two flanks read al-sudufayn or al-sadafayn or al-sudfayn meaning the two flanks of the two mountains he set up bellows and lit a fire around this construction — he said ‘Blow!’ and they blew until when he had made it namely the iron a fire that is like a fire he said ‘Bring me molten copper to pour over it’ the two verbs ātūnī ‘bring me’ and ufrigh ‘pour’ are in contention over this direct object qitran ‘molten copper’; it this direct object has been omitted before the first verb because it is being governed by the second verb. Thus he poured the molten copper over the hot iron so that it penetrated between the individual ingots making a solid single whole.
Logic of the miracle
The verse doesn't say "this is how you prevent rust". It describes a historical event in which a person used this method. And from the verse it seems that it was Dhul Qurnayn's idea (that was not inspired by god). So if Dhul Qurnayn, according to the Quran, was able to come up with this idea, then the Quran disagrees with the apologists who claim that this method was discovered by modern science and ancient people couldn't have known about it.
It was observable in the 7th century that some materials rust and other don't. The idea to put the material that doesn't rust over the material that does rust was not that hard to come with.