Since glass is amorphous quartz and when you slow the cooling of something enough it will crystallize, couldn’t you melt $\ce{SiO2}$ (sand) and then very slowly cool it to cause spontaneous nucleation and form quartz crystals?

If so, then why hasn’t it been used before? It would seem to be a better method than flux because in flux you need many chemicals and a dissolving chemical or mix and it is a complicated and very long process to grow very small crystals throughout the whole mix. If you simply cooled a molten mixture slowly enough to cause complete crystallization, then the entire mix of molten crystal would need to form crystal because it all is cooling down.

  • 1
    $\begingroup$ About the second part of your question, both the α- and the β-phase of quartz have what we call an enantiomorphic space group. It forms spirals that can be 'enantiomers' to each other, which I guess also gives it its properties. For many applications you often need the pure enantiomer which will grow in a seed of the correct orientation under for example hydrothermal conditions. $\endgroup$ – Justanotherchemist May 27 '19 at 8:27
  • $\begingroup$ Melting and cooling will give you a bunch of crystals lumped together. Why would you want that? Then again, I've seen single crystals of quartz as big as a tabletop, and they were not made by melting. $\endgroup$ – Ivan Neretin May 27 '19 at 8:29
  • $\begingroup$ see eg ndk.com/catalog/AN-SQC_GG_e.pdf $\endgroup$ – Buck Thorn May 27 '19 at 8:47
  • $\begingroup$ In principle, maybe. But that isn't how big crystals are formed in nature. Most deposit from solutions not from melted pure silica. $\endgroup$ – matt_black May 27 '19 at 13:03
  • $\begingroup$ @NightWriter Your example post is about hydrothermal growth of a crystal. $\endgroup$ – Buttonwood May 27 '19 at 21:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.