I seem to recall that the metallurgy of the ancient bronzes was
quite variable, and could include all kinds of 'contaminates' as
traces from the original ores; and that occasionally lead was
deliberately added to improve 'pour-ability'; not so great modern
That’s about the size of it. It’s one of the reasons that
archaeologists and museums are now far more likely to use the phrase
"copper alloy" than “bronze”, “brass”, “gunmetal” etc.
For example, the Museum of Fine Arts did an analysis of several
dozen of the copper alloy objects in their medieval collection in the
early 1990s, and found that not only are the copper, tin, lead and
zinc percentages all over the place, often they varied within
individual parts of objects composed of multiple parts. They
published it as part of catalog of the collection. (ISBN
Most of the recent archeology finds, like the work on the Thames,
and York have done similar analysis of the copper alloy objects.
Ron Charlotte – Gainesville, FL