Time to reveal the answer. It's a chemical garden.
Doris and I prepared it for a presentation for our younger grandson's class when we read "Paul Bunyan" to them as a part of the reading program there. In the story, Paul discovers Mammoth Cave and all the crystals in it.
We made it using charcoal pieces, ammonia, bluing, salt and water according to the recipe that went along with the program. The kids loved it and frankly, so did I.
I really appreciate you all playing along with me on this and submitting all your great guesses.
Thanks,
Clark