ashes to ashes

[Steel Tiger]

 I have a burn pile in my field about 50 yards in front of my hives. Yesterday, while mowing, I noticed a couple dozen bees hanging around the ashes left from the last fire. Any ideas on what they might be collecting ash for?

[Colobee]

I've read similar accounts suggesting that it is either some mineral content, or just mistaken for pollen.

[Wolfer]

I live in the country and burn my trash. There's nearly always a couple bees nosing around the ashes.