partly a note to self

[alexseanchai]

so, totally unrelated to anything, does anyone know of resources comprehensible by non-geologists (ideally freely available on the internet—academia.edu counts, as does JSTOR till the end of the calendar year—or at either of the nearby library systems I have cards for) on the sort of geology where amethysts are found?

(I am trying to look for my own worldbuilding resources on JSTOR but there are many and also I am less than thrilled with a search feature that finds me something on reproductive justice because the article has a hyphen and a line break in the word "undermining")

Comments

[eller]

Eh, I am a geoscientist (mineralogist), but I'll try to be as un-nerdy as possible in my answer...
Amethyst is a kind of quartz. The purple color results from iron and irradiation, which does interesting things to the crystal lattice. Quartz is found basically everywhere, so I guess the question is only where you get the conditions to turn it purple.
The pretty quartz, with the large distinct crystals of gem-like quality, is usually hydrothermal. It's found in... bubbles (druses) in volcanic rock, where fluids went through and left the SiO2 behind. So you'd need a volcanic rock that contains iron...
...eh, how much geological detail do you need? XD

[eller]

This is the nerdy version:
https://link.springer.com/article/10.1007/s00126-002-0310-7
The amethysts from Rio Grande do Sul are very typical.

[alexseanchai]

😺

[jenett]

I've been using https://www.mindat.org/ for details for something in the work just finished, which gives locations, but also lots of other useful search terms/details.

[alexseanchai]

ooo shiny