http://en.wikipedia.org/wiki/Transparent_aluminium http://en.wikipedia.org/wiki/Transparent_aluminium "To create transparent aluminium, more power than is used

http://en.wikipedia.org/wiki/Transparent_aluminium http://en.wikipedia.org/wiki/Transparent_aluminium "To create transparent aluminium, more power than is used by an entire city had to be focused into a dot with a diameter of less than one-twentieth the thickness of a human hair, and then could only maintain the transparent state for 40 femtoseconds." And its only transparent to the X-rays that are needed to knock out the electron in the L-shell.