The zodiac goes back almost as far in time as bronze jewelry. The first uses for bronze were not ornamental items but were militant applications such as arrows and spear heads. Bronze jewelry was one of the first alternative uses, since it was soft enough to work easily, hard enough to stand up to a lifetime of use, durable and cost-effective. There were a lot of crowns made from this metal as it can be polished to a golden shine nearly identical to gold.
Copper and tin which are used to create bronze and are rarely found together so serious bronze work has always involved trade. There are many different bronze alloys but modern bronze is typically 88% copper and 12% tin.
I love the weight and look of bronze. It has both warmth and weight and is easily cleaned with a little bronze cleaner called Never Dull which can be found in automotive supply store or Liquid Gold, found in many grocery stores. Bronze will also darken with time turning a chocolate brown. This darkening process is called patina.