A bronze and triptin sculpture
Bronze is an alloy that combines copper with another kind of metal, such as tin.
On Earth, bronze was first used during the Bronze Age of Human civilization. It has since been used in decorations, jewelry and sculptures. During the 24th century the Mintakans and Takarians were considered to be at a Bronze Age-level of development. (TNG: "Who Watches The Watchers"; VOY: "False Profits")
In 2373, a bronze and triptin statue was found on board a derelict freighter in the Bajoran system. Quark acquired the statue, and sold it to a sartorially-gifted Bolian for one bar and three strips of latinum. (DS9: "In the Cards")
Leonardo Da Vinci once had plans for a great bronze horse in Milan, but he never got around to finishing it; in 2374, this was used by Kathryn Janeway to illustrate to the Da Vinci hologram how often he had given up. (VOY: "Concerning Flight")
In 2376, B'Elanna Torres asked Kelis to obtain a piece of metal consisting of three parts tin to five parts bronze, with one side coated with gold, so that she could repair the subspace transmitter on the crashed Delta Flyer. (VOY: "Muse")