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jandrewrogerstoday at 6:32 AM0 repliesview on HN

Everyone targets supergene deposits. They have good properties when you find them. I know of some not on any maps.

Elements run in herds. If you see zinc, you often see lead, silver, et al in significant quantities. If you see copper, you often see gold, antimony, arsenic, et al. Both groups are also often found together. If it is a supergene ore, you also often see hematite, limonite, and other iron minerals.

To see zinc and copper together without being contaminated by the rest of either their herd is actually pretty unusual. You can find samples of zinc or copper individually that have chemistry similar to the target mineral but not both together. Your objective is rare for a reason. From a geochemistry standpoint how this mineral happens is a pretty interesting question.

The chloride aspect helpfully limits the search space. Atacama, including where you found your samples, has massive surface salt domes which is undoubtedly where the chloride comes from. You do not see this in vast parts of the American copper belt that are otherwise rich in zinc and copper. That might actually be a way to target it in North America but I suspect it isn’t well-mapped. It would require a modicum of research. On the other hand, it isn’t well-mapped in South America either. I know about it because I was there.

I am a chemist by training and a geology nerd. I’ve also spent an inordinate amount of time in both the Atacama and the American Mountain West, both of which are prime search areas. It is probably possible to develop a heuristic for locating concentrated deposits of this specific mineral but that is a research and exploration exercise on its own.