And, as always, The Rockhounds Group goes for Teh Win!
From the abstract:
The unusual color of the "Blue Dragon" lava is due to intense blue light being reflected from clusters of tiny titanian magnetite crystals, which, together with crystallites of plagioclase and olivine, are dispersed throughout an outer layer of clear brown glass. It is proposed that Fe'* -> Fe8*, and probably Fe'* -> Tia*, electron transfer processes are responsible for the blue color.
Looks like I was partially correct... the blue IS a glassy surface. However, it's NOT an iridescent sheen as with a film of oil. It's a reflection off of teensy-tiny (techy phrase, eh?) layer of magnetite crystals.
Ain't science grand?