Tinkerisk:They produce one with 100% cocoa content.
Someone brought some 99% in to work a while back. I noticed its presence when I saw a cow-orker walk past trying to scrape the surface of his tongue off with his fingernails. Suitably forewarned, I took the tiniest flake of it I could possibly break off, maybe 1-2 grams.
I've never actually chewed a piece of charcoal before, but I now have a pretty good what it would taste like.