I'm wondering if anyone knew of a chemical spot test to distinguish zinc vs aluminum (coatings,die castings, etc.) I'm thinking maybe a 30% nitric acid dip--aluminum would be unfazed, but the zinc would be rapidly dissoved?
Please note that a special coating called Galvalume, covered by ASTM A792, indicates a material for dip coating made of 55%Al-45%Zn.
I recommend X-Ray fluorescence as the best nondestructive instant test for positively identifying most of metals.
Many labs and facilities (even junk yards) can offer this test at nominal cost.