Henry, masterfully done, especially considering it is an experimental medium for you.
Of the charcoal family, I use vine charcoal exclusively, on coarse charcoal paper. My drawings are ten minute wonders, for public performance. I always had bad luck with charcoal pencil and compressed charcoal. The charcoal pencils are the paper wound ones, right? You tear a little string, then unwind the paper, then the charcoal falls out, and you tear a little more, unwind, then the charcoal falls out, and so on. Thus, I use vine.