rock salt is better than sea salt

This statement is not definitively true. Rock salt and sea salt have distinct differences, but neither is objectively "better" than the other—it depends on your priorities and use case.

Nutritional and Chemical Composition

Rock salt and sea salt are chemically very similar. Both are primarily sodium chloride, and nutritionally, they're essentially the same[3]. Both contain trace minerals like zinc, copper, iron, manganese, potassium, and calcium, though the amounts are minimal and unlikely to make a significant health difference[3].

The key distinction is that sea salt naturally contains iodine, iron, sulfur, and magnesium because these elements are present in seawater[2]. Rock salt, by contrast, contains no natural iodine since there are no iodine deposits in ancient soil[2]. This means rock salt often requires industrial iodization for food use, whereas sea salt obtains iodine naturally from the ocean[2].

Origin and Processing

Rock salt is mined from underground deposits left by ancient oceans that evaporated millions of years ago[1]. A significant advantage of rock salt is that it formed so long ago it's theoretically free from modern pollutants[4]. Sea salt, conversely, is created by evaporating modern seawater and may potentially contain contemporary contaminants, though evidence suggests the quantity would be negligible with reasonable salt consumption[3].

In terms of processing, sea salt is typically less refined than table salt but still undergoes less processing than industrially-produced rock salt varieties[1].

Practical Considerations

For culinary use, rock salt and sea salt both offer coarser grains that can add texture and visual appeal compared to table salt[3]. Sea salt tends to have larger, irregular crystals and a brighter, crisper flavor[1].

Neither salt is objectively superior—the choice depends on whether you prioritize natural iodine content (favoring sea salt) or freedom from modern pollutants (favoring rock salt).