Those 6 tankards have got to be pewter. Pewter, aluminum and ones that look like the Pewtarex stuff are what is out there for tankards.
- The aluminum ones will also have a glass bottom, but will be very light, with a riveted on handle and usually say "made in Hong Kong" on the base.
- The ones that look like Pewtarex (not pewter) are very thick with a pitted look to the metal and dont have a glass bottom, plus you can see the lines where sections where molded and fused together.
- I have seen one lead tankard and that was very heavy.
- There are some pewter tankards that arent marked but they have the same characteristics as the ones that are marked.