Eggses!

These are chicken eggs I bought from a local woman who raises free-range, grain-fed chickens. Notice that they are not uniformly white or brown. I didn't even get the most colorful dozen. Her hens lay eggs in many shades of pink, blue, green, brown, and white, and I would like to know why.

I suspect that the minerals in their feed and in the soil tint the shells. That is a pretty large hypothesis, though, so I should narrow it down. Are all of the chickens the same breed? From the same clutches? Are they all fed the same thing every day? What are they fed, and how much? Do they all spend the same time outside each day? What kinds of worms and grubs dwell in the soil? Do some chickens eat more worms and grubs than grain? As you can see, there are plenty of variables that need to be controlled in order to answer this question, and some of them might involve discomfort or inconvenience to the farmer or the chickens.

There is one non-invasive thing I can do though. I can save the shells, dry them out, crush them to powder, and burn a bit of the powder while observing the flame through a spectroscope.