Yellow bronze

What exactly is yellow bronze? I made an inquiry about a toggle clasp
and was told it’s yellow bronze with a little bit of copper in it, no
brass present. Huh? So that would make it (mostly) copper with tin or
zinc?

Thanks for any comments anyone can make, Carol

Copper alloy nomenclature can be confusing! Brass is nominally copper
and zinc. Classic bronze is nominally copper and tin. Then it gets
confusing—commercial bronze is 90% copper 10% zinc. Copper alloys
lose the copper red color quickly when combined with other metals.
Yellow brass can be a lot of things but it is generally called that
at about 65% copper 35% zinc. The best web source on copper alloys
is: http://copper.org the site has a lot of but it may
take
a little looking around it.

jesse