What kind of African blade is this?

[Tim Simmons]

Looks like a form of brass or bronze. Brass being copper and tin and bronze copper and zinc. These alloys can become similar when alloyed with other metal. Either brass with zinc of even lead and bronze with tin and or lead. In industry this depends on what the alloy has to do. In a piece like the example you show the alloy might be what is commonly at hand.