Please find my answers below :
Description: Red salt is the traditional salt used in Hawaii. It is Pacific sea salt combined with purified red Hawaiian clay. The clay is rich in minerals and also acts as a natural flavor enhancer. The dramatic color also makes it a popular choice for garnishing.
My supplier also gave me the following information:
The clay is backed for purification and its content in the salt is less than 0.5% by weight.
I hope these information will be useful.
Have a nice week,