Five sites are listed and one of them is Searles Lake and Trona.
The dry lake is full of minerals – mostly salt and boron – that can be processed into industrial and consumer products, such as compounds like borates (boric acid and borax) and sodium carbonate (soda ash) and sulfate – major ingredients in detergents and other cleaning products. In fact, Searles Lake contains one of the world’s richest deposits of naturally occurring minerals.
https://www.kcet.org/shows/socal-wanderer/where-to-find-socals-most-fascinating-mining-destinations