Norman's complaints that lead atoms are too heavy do not seem consistent with the composition of other known superconductors. As far as I know, the most widely

Norman's complaints that lead atoms are too heavy do not seem consistent with the composition of other known superconductors. As far as I know, the most widely used cuprate superconductor is bismuth strontium calcium copper oxide (BSCCO), which was used for the world's first superconducting power line: https://en.wikipedia.org/wiki/Holbrook_Superconductor_Project https://en.wikipedia.org/wiki/Holbrook_Superconductor_Projec... >What’s more, lead and copper atoms have similar electronic structures, so substituting copper atoms for some of the lead atoms shouldn’t greatly affect the electrical properties of the material The lead (II) ions claimed have an even number of electrons. Copper (II) has an odd number. Or if copper (I) is present, then the charge itself is different. Again, this is just a very confusing argument to hear from a physicist. >First, the undoped material, lead apatite, isn’t a metal but rather a nonconducting mineral. The cuprate and iron superconductors are not metals either. In fact some are Mott insulators (materials with unexpectedly high resistance) under normal conditions. There is a case for skepticism about LK-99, but it isn't this one.