If I Have A Tarnished Piece Of Metal How Do I Know If It Is Copper, Bronze, Or Brass?

Bronze and brass are both copper based alloys. The difference between the two lies primarily in the greater content of zinc used in brass. Typically brass has one part zinc to two parts copper while bronze has eighty to ninety per cent copper mixed with tin and or lead with very little zinc. However different types of brass and bronze have different mixtures and brass castings have eighty four per cent copper with equal parts of zinc tin and lead. Bronze is typically darker than brass and is also harder. However due to the various different grades it can sometimes be difficult to tell them apart. You cannot really tell all three apart by appearance, and would need scientific analysis to be positive. Copper will corrode faster than either brass or bronze. The corrosion products often appear as bright blue or green areas on the object.

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