Land based sea salts mined from ancient sea beds such as Himalaya sea salt or Redmond Real Salt are preferable due the alarming pollution in our oceans today. (thehealthyhomeeconomist.com)
The opal is mined three to 10 metres down on ancient sea bed of one point eight million to 700 million years ago. (wikiaustralia.com)
I would not recommend colloidal minerals from ancient sea beds. (myersdetox.com)