lil’ bit of copper in that one...
You are probably correct. Some other metals will ionize to a blue color but the most likely for this comet is copper.
Several metals impart a blue color when ionized, notably copper(I), arsenic, cesium, indium, lead, tantalum, and cerium.
Beautiful shot. I really like the sequences of comets he has on his Astrobin page, illustrating the cometary structures over time.