yeah, sir it looks like this old man is well aware of these minerals and salts and it not easy to search them and them working hard to dig them out, it is not one salt or mineral, they are in bulk and imagine the hard work this old man has done in searching and digging out these beautiful precious minerals, yes people do buy these salts and minerals to cure some decrease, you should believe it. as far as stone concerns people use stones according to religious beliefs. Our holy bOok QURAN has tell us about two precious stones Yaqoot and Marjaan__, They are precious for Muslims as according to their religious belive, some of them use stones when they found them beautifiul and attractive.
thank you sharing this wonderful place and thanks for telling us about this hard working old man, my prayes are with him, May God bless him always.