Salt is one of those absolute bottlenecks for most people not living near the coast.
You can grow or hunt food, there is always 'some' source of water, rain, groundwater, something.
But without a natural salt deposit, its game over. We need vast amounts of salt to survive, relatively speaking. (compared to other minerals)
This is before you get to its use a preservative, tanning agent, or simple flavoring.
And its dirt cheap, currently.
As a barter item, the return on investment could be enormous. Orders of magnitude more than gold.
When uncontacted amazonian tribes where introduced to civilization, the thing they where the most impressed with was our access to salt.
The Lewis and Clark expedition, was not to explore America, it was to find a mythical (as it turned out) mountain of salt. That was what the investors where hoping they would find.
The importance of salt cannot be overstated.
And few preps are easier to store. It never goes bad, is not damaged by hot or cold temperature, and even if it gets wet, is not destroyed unless literally washed away. You could stack hundreds of pounds of it on a pallet, under a tarp in your backyard, and it would still be viable after many years.
