Correct me if I’m wrong but this big purple slab of quartz is an Amethyst crystal. It’s in the Hall of Minerals at the Museum of Natural History. It sits there, strangely illuminated in the dark, illuminated from an external lighting source. We are attracted to its color and form –a non-organic thing in the midst of life and the living. By disposition and professional training, I regard it from the perspective of religion and religious studies. Is it an icon of or an index to something “supernatural”?
Geologist Robert Hazen & colleagues have put forward the hypothesis that the presence of so many varied forms of minerals on Earth is actually driven by evolution of organisms. For example, amethyst is a form of quartz (Si02), which could only have formed after photosynthetic bacteria produced enough atmospheric oxygen for it to react with minerals in the crust.
https://www.quantamagazine.org/20150811-mineral-evolution-of-earth/