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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

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 https://en.wikipedia.org/wiki/Kyropoulos_method --- Seems like it already is: https://en.wikipedia.org/wiki/Quartz#Synthetic_and_artificial_treatments https://en.wikipedia.org/wiki/Quartz#Synthetic_and_artificia... No mention there of purity though.

throwup238 2y ago
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.
- foreverobama 2y ago
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KeplerBoy 2y ago
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 2y ago
  They seem pretty ugly if they're not cut. ;) https://www.youtube.com/watch?v=-INytU_pdkg https://www.youtube.com/watch?v=-INytU_pdkg
pjc50 2y ago
The https://en.wikipedia.org/wiki/Czochralski_method 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.
adrian_b 2y ago
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.

throwup238 2y ago

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.

foreverobama 2y ago
[dead]

KeplerBoy 2y ago

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 2y ago
They seem pretty ugly if they're not cut. ;) https://www.youtube.com/watch?v=-INytU_pdkg https://www.youtube.com/watch?v=-INytU_pdkg

pjc50 2y ago

The https://en.wikipedia.org/wiki/Czochralski_method 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.

adrian_b 2y ago

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.