Note that the following metals are alloys of the above:
- brass - copper/zinc
- bronze - copper/tin; usually, 90%+ copper (common is 95%)1
- electrum - silver/gold
Also note that although aluminum and titanium are quite common in the Earth's crust, they do not occur naturally in a metallic state. Their manufacture was not mastered until the 20th century. (Aluminum was first easily produced by Charles Martin Hall in the town of Oberlin, OH.)
1. Sometimes metals other than tin are used, although tin is the most common.