No, they'll both have a mass of an ounce. Their weight - the force exerted on them by gravity - differs, due to the different uplift by the air around them. As I mentioned before (assuming this post doesn't beat my last one) I'm assuming uncompressed feathers.
Ian
..and what happens if the ounce of gold is in golf leaf form? Surely then, the surface area of gold would be larger than the surface area of the feathers and so, the uplit force due to air would be greater on the gold.
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