So I'm moseying around on the Internet and a link takes me to the King Arthur site.  Okay, while I'm here, I'll see if they have anything new or interesting.  And I come across Bread Salt.

http://www.kingarthurflour.com/shop/items/bread-salt-16-oz [1]

The blurb calls it "An all-natural salt that's ideal for bread baking."  It also says "[Its] high mineral content helps feed yeast in a rising loaf. "

Questions:

(1) What makes this salt so special?

(2) Helps feed yeast?

Rosalie