Burning magnesium in dry ice (video)
Caution: this reaction produces an intense white light and substantial ultraviolet light that you can not see but can damage your vision. Although the dry ice absorbs much of this, do not allow anyone to stare at the light at its brightest.
Yes, magnesium will burn merrily in a block of dry ice; oxygen is not the only oxidizer in town.
Last January, among other things I demo’d for the 8th graders in Physical Science magnesium burning in dry ice (CO2). It’s a beautiful and impressive experiment that I have done many times, not to mention dangerous if mishandled. The boys helped videotape the practice session in our kitchen, and I added captions. I used about half as much magnesium in class, or 3 grams — a lot of “smoke” is evolved and I didn’t want to spark an evacuation. The energy released is substantial — over 100 kJ here (my rough calculation).