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If I were to use handwavium to raise a volcano in the middle of the sea, would it contain metals or ores large enough to be extracted by normal means, like mining with a pickaxe?

Everything apart from me ordering nature to make a new volcano would be natural processes. The process will take 100 years and after that the volcano will be as big as old Krakatoa. Once it reaches a desirable size the volcanic activity will stop and the whole thing will start cooling down. The inside of the volcano is filled with gas and once it cools down the top of the volcano will collapse.

Could there be metals inside? If it was a volcano with a lava pool in the middle will there be metals inside?

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    $\begingroup$ what do you mean by "metals"? Do you mean nuclei of elements that are classified as metals, solid bulk metal or relatively pure molten metals? Maybe something else? Please specify. Also if you go for solid metals (which I think is most likely), are you asking if there is a metal with a melting point higher than the temperature of lava (yes there is) or do you want to know if such a thing is likely or how it could happen geologically? $\endgroup$
    – Raditz_35
    Mar 13, 2018 at 12:33
  • $\begingroup$ Same doubt as Raditz's, but in other words: do you mean usable ores? $\endgroup$
    – The Square-Cube Law
    Mar 13, 2018 at 12:35
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    $\begingroup$ @NuloenTheSeeker Since you went for that option, have you tried a google search? I have (I have to say it's something I did not know and found interesting) and without any trouble it came up with multiple results that answered your question. It is encouraged to do some research before asking a question $\endgroup$
    – Raditz_35
    Mar 13, 2018 at 12:40
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    $\begingroup$ I'm voting to close this question as off-topic because questions about the contents of volcanoes belongs in earthscience.WB. $\endgroup$
    – RonJohn
    Mar 13, 2018 at 17:02
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    $\begingroup$ @RonJohn WB stands for what? Worldbuilding? $\endgroup$
    – Vincent
    Mar 13, 2018 at 18:22

2 Answers 2

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First a mineral brine occurs over millions of years, then you bring your volcano up through it and convert the brine to sulfide ore.

It is known that metals like copper and gold occur in association with volcanoes.

https://en.wikipedia.org/wiki/Porphyry_copper_deposit

Porphyry deposits represent an important resource of copper; however, they are also important sources of gold and molybdenum... Porphyry deposits are formed in arc-related settings and are associated with subduction zone magmas. Interestingly, porphyry deposits are clustered in discrete mineral provinces, which implies that there is some form of geodynamic control or crustal influence affecting the location of porphyry formation.

These scientists have laid out a model for what those geodynamic controls are.

Generation of porphyry copper deposits by gas–brine reaction in volcanic arcs

Porphyry copper deposits, that is, copper ore associated with hydrothermal fluids rising from a magma chamber, supply 75% of the world’s copper. They are typically associated with intrusions of magma in the crust above subduction zones, indicating a primary role for magmatism in driving mineralization. However, it is not clear that a single, copper-rich magmatic fluid could trigger both copper enrichment and the subsequent precipitation of sulphide ore minerals within a zone of hydrothermally altered rock. Here we draw on observations of modern subduction zone volcanism to propose an alternative process for porphyry copper formation. We suggest that copper enrichment initially involves metalliferous, magmatic hyper-saline liquids, or brines, that exsolve from large, magmatic intrusions assembled in the shallow crust over tens to hundreds of thousands of years. In a subsequent step, sulphide ore precipitation is triggered by the interaction of the accumulated brines with sulphur-rich gases, liberated in short-lived bursts from the underlying mafic magmas.

In sum: a subsurface brine accumulates dissolved metals over a long period. Mineral brines might be forming all over the world regardless of volcanism. But if there is then an uplift of magma and sulfur rich gases into one of these collections, the minerals precipitate abruptly into the sulfide ores and are carried on up and out by the magma. If your new volcano happens (or is positioned) to be coming up underneath a brine deposit like this, there are your metals.

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  • $\begingroup$ No, that's not how it works. The sulfur rich gas emerges from shallow magma into the brines, passing through the rocks, causing metal precipitation in situ, not carried by magma out of an active volcano. That's why they formed at depths of 1 to 6 km: any found near-surface is because of uplift and erosion, not volcanic action. The deposits require an intrusive magma: if it's extrusive, the gases don't have to percolate through the brine-filled rock because they can take the much easier route out the vent. $\endgroup$
    – Keith Morrison
    Mar 13, 2018 at 22:22
  • $\begingroup$ @Keith Morrison - is the arrival of the gas a precursor to the volcano? Are subsurface intrusive magmatic (is that a word?) phenomena precursors of extrusive phenomena? I think the precipitation of metal sulfides would probably happen fast. $\endgroup$
    – Willk
    Mar 14, 2018 at 13:38
  • $\begingroup$ Intrusive events are a necessary precursor extrusive events, but an extrusive event is not necessarily the result of the former. That aside, there's been no significant metal deposits found "inside" an extinct volcano, ever, that I'm aware of. Given the sample size, it seems reasonable to assume your scenario doesn't happen. $\endgroup$
    – Keith Morrison
    Mar 14, 2018 at 14:12
  • $\begingroup$ To be more specific, metals can be found associated with extrusive events: the Muskox Intrusion, with its metal deposits, is believed to have formed within the magma chamber that fed the Mackenzie Large Igneous Province, but the metal deposits formed as the chamber was cooling and solidifying, not from the magma actually erupting out. $\endgroup$
    – Keith Morrison
    Mar 14, 2018 at 14:18
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The metals won't be inside, and they won't be there in a short span of time.

Volcanogenic massive sulfide ore deposits are formed by hydrothermal systems (obviously powered by magmatic heat) that causes water to leach metals from within volcanic rocks and then precipitate out when the hot water hits cold sea water in a black smoker field. This concentrates the metals that were otherwise distributed through the volcanic rock into ore deposits that are mineable.

But this takes time. You're looking at centuries for the leaching and deposition process to take place.

Volcanoes don't have metals conveniently concentrated for you right from the start.

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    $\begingroup$ Good answer, though I think I'd change "centuries" to "millions of years". But I'm not a geologist :-) (And for the OP: if volcanos had concentrated metals or ores, you'd find mines there...) $\endgroup$
    – jamesqf
    Mar 13, 2018 at 18:46
  • $\begingroup$ I am a geologist. $\endgroup$
    – Keith Morrison
    Mar 13, 2018 at 22:13

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