I am a blacksmith, I would know this one. Alright... Aluminum, has a great shine to it, and it looks like silver... Same with tin, except aluminum is super shiny and sleek, while tin has a dull shine to it. Steel, is flat (color-wise), and it has a slight shine to it.
You can find what type of metal it is by color, shine, light reflectance, dullness, and several other properties. Hope I helped you! :)