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How can you tell if a penny is copper or brass? 

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The analysis of a simple brass gave an excellent result for the determination of copper and reasonable results for lead and zinc determinations.
Both these salts and other greenish, synthetic copper-containing compounds may be products deriving from artificial corrosion of brass or other copper alloys.
As a result, the coated brass with copper content of 60-70% is effective and the thickness of coated brass is needed to be more than 1.45μm for high removal rate.
This result differs from experimental data that show less copper-type and more brass-type textures in both phases for the composite materials.
The equilibrium diagrams are in agreement with the reported behaviour of brass in copper-containing 15 M ammonia, and with the active behaviour of zinc.
However, the dissolution mechanism of the Cu component of brass is the same as that observed for pure copper.

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