We have made fire from ice twice-
Once at our studio-
We carved a sphere & placed it in the sun
60F @ 5:00pm we made a smiley face in under a minute
Try holding your hand there for more than a few seconds!
The other time was in Alaska
Using a giant potters wheel style lathe, Russ & I made this lens
Even @ sunset this 4′ lens produced heat
At mid day it could ignite paper, light a cigarette, & burn drywall.
This was one days burn