Nothing is pure, not even crystals, which are by definition all about the stability and structure of their makeup. They're awesome to pore over at a museum, and they can be a great jumping-off point for personal reflection, if you're into that. The ones you can buy, however, may not be so fair-trade and ethical as any of us would like.
Crystals, like most minerals, are the product of some kind of exploitation, whether it's through the environmental degradation of mining or labor violations all along the supply chain. The Guardian went so far as asking whether crystals are "the new blood diamonds," citing celebrity endorsements (Gwyneth Paltrow, Adele, an array of Kardashian-Jenners) and wellness grifters, a sharp untick in cultural cachet driving billions of dollars in sales. Even "fair trade" is a bit of a squishy label, as anyone knows who's ever tried to untangle what "organic" means or whether your meat is ethically raised.
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The business side of crystals is pretty opaque about its sourcing, but that doesn't mean you have to compromise your interest in them — or whatever you've found about them that helps you. The diamond industry, for instance, is working on normalizing lab-grown gems. Crystals grown "artificially" are exactly the same as those that are found in nature; all that's changed is the time scale over which they develop. Look for words like "synthetic" or "created gems" while you're shopping. Whether your interest in crystals is spiritual, scientific, or aesthetic, it might be worth hunting down the ones that make you feel best.