So am I correct in guessing it at least (if quartz sand) can be used for microchips and the likes? I hope the rough sands aren’t extrated just to be used in something, were other, less scarce sands could be used - but I could at least imagine stuff like economy of scale, existing infrastructure and special interest of the established industries could actually cause that.
I ran an instance for a while out of curiosity a few years back - building the database seemed to work fine and appeared like a good idea, had a lot of fun to see the connections with other servers and my crawler filling holes of unknown spaces. But I think the search algorithm itself was (most likely is) not sophisticated enough, it just did not give relevant results often enough, and it was extremely vulnerable to very simple SEO tactics to push trash to the top.