@lain @alex You know, we've had processes to manufacture high quality artificial quartz since the 70's. Pretty much all technical uses of quartz, including oscillators, use lab grown stuff.

Same with ruby and sapphire. Heck, tons of places will sell you big sheets of the stuff: https://www.uqgoptics.com/catalogue/optical-windows/sapphire/

Air is really useful. But it's also essentially worthless because we have so much of it...