Updated status in third fourth post. Not finished yet, will keep working on it. Might try this again for next year. Thanks all for the help and for reading.
But crystals aren’t as good heat conductors as metals, are they?
Is this really a crystal or pure quartz glass like good chemistry equipment? The difference is that crystals have the atoms arranged in a repeating pattern but glasses have them in a sort of random order. I think it would have to be cooled slowly to form as crystal, maybe even pulled out of a melt as it hardens like silicon or germanium. (Iron has to be cooled very quickly to form a metal glass.)