We have a few questions about crystal formation and properties, for example:
- Why does the colour of amethyst fade if exposed to too much light?
- Why do crystals, like quartz and diamonds, form in different colors?
- How and where do double-terminated crystals form?
My feeling is that all three of these questions would be better suited to Chemistry.SE. However, I can see that there may be other cases where crystal-related questions might be more geochemical. Anyone have any ideas for guidelines on how to decide when a question like this is more suited to Chemistry.SE or here?