How do they know they were King Solomon’s mines? The only mention of a nation or people is that Egyptian artifacts were found. They may be calling them King Solomon’s mines to facilitate future funding.
Good question. Initial news stories on academic discoveries are to be taken with a grain of salt. And from what little I know about archeology, there is often a lot of guess work based on arbitrary smatterings of data here and there.
Fortunately for some things there are some pretty good written records. For instance, there simply isn't any good reason to not believe there was a very wealthy Hebrew King named Solomon, except for people who have an irrational bias against the Hebrew Bible.