Why blue?

A recent comment asked why the ice in the previous post is blue. We have always figured it was because it picks up minerals as it flows through the ground on its way down the hill. This road cut is along the highway at the front of our property and the water that flows out of it comes from under a maple woods where a fellow we know taps our maple trees for maple syrup (and gives us a couple of gallons each year for the privilege.) Above that woods is a good alfalfa field on fertile slate ground, some of the best we have. The low quality of forages in NY in the past couple of ridiculously rainy years attests to just how many nutrients are leached by excess water. Why wouldn't that make the ice look different?

Just to be sure we were correct in our assumption, I did some research on blue ice. (Did you know that there is software with that name, and rappers as well. I sorted through a mountain of dreck before I came up with anything remotely useful.) I found lovely pictures of ice. Then I found this, which really doesn't seem to explain our ice, since there are sections that are just as thick adjacent to the blue ice that are plain white. And this, which shows black ice. Here are more links about ice color. I guess you can take your pick of theories.

I am still inclined to think ours comes from minerals, as the blue occurs right next to plenty of plain old white and some that is just sort of dirt-colored, probably from dirt. Anyhow....

Thanks, Laurie, for an interesting question.