The way you approach the texturing of these objects will be down to the game engine. Please check what the engine supports with regards to the textures.
Most engines support the basics. but if you are looking for good reflections then the indie engines are limited to these more advanced features.
I would get a texture file (gif, jpg, png - these are engine specific) for both gold and copper (try the Autodesk "The-Area" Website, get a bronze membership (It's free) and search the metals for the ones you are looking for), UV map them onto the geometry via a Blinn or Phong Material, to get you sum reflectivity, and test it in the engine.
Chris (formerly R@nSiD)
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Winner SM VFX Challenge 1
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