X-ray vision of superman: Is lead the only element stopping the ability?

Question

I know that in the fictional Superman universe, "X-rays" do not work like real X-rays (color, translucence etc.), but for the reader's sake the authors invented the inability to see through lead.

Now is lead not the only substance which is very good to stop X-rays, but all elements with high atomic numbers (many electrons to scatter the radiation). This is hafnium, tantalum, tungsten, all heavy platinum metals, gold, mercury and uranium.

Are these metals ever mentioned to have a similar effect of blocking X-ray vision or are there egregious examples where pieces of the metals above are transparent like glass?

Or are there other fictitious or real materials known to block the vision? In at least one instance I remember people from the far future are sending waste back by time travel and superman encountered a "meteorite" which was so dense that his X-ray vision was useless.

Just curious.

Answer 1

Superman has, over the years shown an ability to see through a wide range of metals and substance that should (under normal circumstances) block X-Rays.

There are, however a very rare number of occasions when his X-Ray vision has been blocked by non-lead materials;

• In the video game, Superman: Shadow of Apokolips, he's unable to see through Lois Lane's skirt, presumably for the sake of decency :-)

• In Superman #250, Supes encounters Terra-Man. His outfit is capable of reflecting Superman's X-ray vision. No explanation is given regarding the substance used:

He also (in Smallville) seems to show something of an inability to view through Kryptonite.