by adrian_b | 2025-11-08 10:39:18+00:00
The native metals are either too soft for being used for tools (Cu, Ag, Au) or too hard to be possible to forge (platinum-group metal nuggets, which were the material originally named "adamant" by the Greeks, before the Indian diamonds became known after the expedition in India of Alexander the Great).

Native metals have always been used only as jewels, before it became possible to melt them, in order to make hard alloys, e.g. copper-arsenic or copper-antimony, and later copper-tin.

The exception has been meteoric iron (i.e. Fe-Ni-Co-Ge alloy), which is hard enough to be useful (because it is an alloy), but that could never be an abundant resource. Moreover, meteoric iron cannot be forged without heating it. Cutting and polishing it like you do with stones is very difficult, but possible. However, such a method of using it does not provide the main advantage of metals, of enabling the creation of complex shapes by plastic deformation. Had it not been possible to forge meteoric iron by heating it in fire, nobody would have bothered with attempts to make knives out of it, instead of using stone tools.

Using concentrated light instead of fire would work, so such an invention could be imagined on a planet where the atmosphere could not provide fire, like on Earth. However this is not something that could be invented by aquatic animals, because they would have to invent first means to make chambers empty of water where materials could be heated in such a way. Such a succession of inventions, including adequate pumps, is extremely implausible because their utility would not appear until all the necessary techniques would exist. It would be far more plausible for aquatic animals to first develop means to live outside the water, and only then make such inventions, in an environment where they are much easier.

While there are bacteria that can reduce some metal ions, e.g. of copper, silver or gold, to the corresponding metal, they do not do this for producing a metal, but for removing poisonous ions from their environment by sequestering them into the insoluble metal. On Earth, living beings have either a complex structure or chemical versatility, never both. It seems likely that this constraint would also exist elsewhere, so one should not expect intelligent beings that are able to reduce metal ions into metals by their body physiology. In any case, the pure metals produced in this way, like also the native metals precipitated in abiotic conditions, are useless for making tools, without being able to heat them to high temperatures for making alloys and for controlling their polycrystalline structure. The same applies to metals that would be produced by electrolysis.

Fire using air is the source of heat originally used by humans on Earth. Any other available source of strong heat could have replaced it in the history of another planet. The point is that to ascend to the level of human technology any living being must acquire the capability of processing materials at temperatures very different from their ambient temperature. None of the techniques of producing metals at the ambient temperature is sufficient for being able to make useful things out of them. The same for other classes of materials, e.g. semiconductors or glasses.

One could imagine an extremely advanced technology where one would be able to make a big object by putting an atom after another in just the right place. That could work at ambient temperature and produce anything. Even if such a technique were possible, I find it impossible to believe that any living beings could become capable to develop it without first passing through the stage where a lot of material transformations can be made only at high temperatures and/or high pressures.