Sqwertz wrote:

Would it be the impurities it the sea salt that would
presumably cause it to darken? My brand of sea salt it
cleaner than most (La Baleine).

What else could it be? Pure sodium chloride won't be
affected by any temperature you can reach in your
kitchen. (Perhaps not my kitchen, but I've got stuff
I bought off eBay that can vaporize salt. :-)

And would toasting salt really affect the flavor?
I would think the impurities would just burn, which would
have drastically different results (maybe good, probably bad)
depending on where the salt came from.

If it's got those impurities, roasting is good.
The impurities may include untreated sewage,
which is better roasted.