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The 54 periodic elements used in processors to 2005/6 (via chief IBM IC developer)
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has 30 of which (incl. above) could get 13 more
Lutetium Dysprosium X Erbium X Gadolinium HAVE Yttrium X Cobalt X Magnesium HAVE Niobium X Calcium X Antimony Titanium X Bismuth X Chromium X Cadmium Manganese Aluminium X Tin Zinc HAVE Lead Iron Carbon X Sulphur Nickel X Molybdenum X Tellurium Gallium Mercury Tungsten Selenium Silicon HAVE