[bigbillheck]

> If not, wouldn't you expect to hear about...

I've certainly heard about such:

https://www.usgs.gov/mission-areas/water-resources/science/a...

> lead, being heavier than water, drop out of the groundwater

Sodium chloride is over twice as heavy as water, and yet doesn't 'drop out' of it.

[anthonyu]

A bit of a bad analogy as, in water, the sodium and chloride are not bound together; rather, the ions are separately distributed throughout and wouldn't have the same density that they would have in a dry, crystal, ionically bound form.