Ancient pewter is an alloy of tin and lead, much used in Roman times, and from the Medieval to the 18th century. The poisonous nature of lead has resulted in the replacement of lead with antimony, although antimony is also inadvisable in high amounts for cooking utensils. Roman pewter appears to have included three different binary tin lead alloys, the groups covering the range 30 to 50%, 69% to 80% and greater than 90% tin. The first group would seem to correspond to Pliny’s 50-50 alloy, but the second has a higher tin content (nearer to 3 tin to 1 lead) than Pliny’s second alloy of two tin to one lead. ( Pollard 1983 and Hughes 1980)
Some Romano-British and medieval pewter has been found to contain an appreciable amount of copper.
Modern lead-free pewter is basically tin with variable amounts of copper and/or antimony to harden the metal or alter the casting characteristics. Such alloys may contain between 0.5-2.5% copper, and 0-10% antimony