[throwup238]

We can but synthetic quartz faces the same problem as hydrocarbon fuels: we can make synthetic natural gas if we use enough energy, or we could exploit the geological processes that created it over millions of years and extract it.

High-purity quartz from areas like Spruce Pine typically forms in pegmatites, where slow cooling of magma allows large, defect-free crystals to form. Hydrothermal fluids permeate these rocks while they’re cooling, effectively leaching out impurities. If the geochemistry is just right, over millions of years, this process repeats several times creating very high purity quartz deposits that are very difficult to replicate in laboratory conditions.

[justinclift]

Any idea how big these quartz crystals needs to be?

Single crystal sapphires ~250kg are grown in production, so it should be possible with reasonable effort to do similar for quartz:

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

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Seems like it already is: https://en.wikipedia.org/wiki/Quartz#Synthetic_and_artificia...

No mention there of purity though.

[pjc50]

The https://en.wikipedia.org/wiki/Czochralski_method is the actual big crystal growing process, to which this quartz is just the input. Effectively we repeatedly make a crystal with the impurities moved to the end, then saw off the end and discard it, then re-melt the crystal to make it even purer.

[throwup238]

It’s not the size that’s hard but the 99.9999% purity. The quartz from these mines is crushed, sorted for impurities, and fused/annealed into larger crystals before they’re ready for the semiconductor industry.

[adrian_b]

The single crystals of silicon that are made are cylinders with a diameter of 0.3 meter and a height probably of around 2 meter or even more.

The crucible must be bigger than that. The crucible is made from fused quartz glass. So the mine does not need to have big quartz crystals. They must be only pure. The mined crystals are melted together and processed like any glass, except that processing quartz glass is difficult, due to the very high melting point and the high viscosity of the melted quartz.

The melting of the pure quartz requires itself a crucible made from materials that resist to even higher temperatures, e.g. a crucible of molybdenum or even a crucible of iridium, for the lowest contamination with impurities.

[KeplerBoy]

Well that's not nearly as neat looking as I naively expected a large sapphire to look like.

I suppose the usual gem color arises from the impurities?

[justinclift]

They seem pretty ugly if they're not cut. ;)

https://www.youtube.com/watch?v=-INytU_pdkg

[westurner]

Can nanoassembly produce quartz more efficiently?

/? nanoassembly of quartz https://www.google.com/search?q=nanoassembly%20of%20quartz mentions hydrothermal synthesis,

Which other natural processes affect the formation of quartz and gold?

From https://news.ycombinator.com/item?id=41437036#41442489 :

> "Gold nugget formation from earthquake-induced piezoelectricity in quartz" (2024) https://www.nature.com/articles/s41561-024-01514-1 [...]

> Are there phononic excitations from earthquake-induced piezoelectric and pyroelectric effects?

> Do (surface) plasmon polaritons SPhP affect the interactions between quartz and gold, given heat and vibration as from an earthquake?

> "Extreme light confinement and control in low-symmetry phonon-polaritonic crystals" like quartz https://arxiv.org/html/2312.06805v2