Both are anodized aluminum. Anodization is a chemical process that replicates natural aluminum oxidation, but done to enhance (since many colors can be used) the beauty of Al and to increase wear. It normally takes years or really tough use to wear through. It's not paint that flecks off. I've seen evidence of scuff gate in the store. Apple has years experience with anodizing Al. My 2009 MacBook Pro has NO worn sharp edges. It is Al anodized silver ( we call white here: it's a white phone and silver back side). Wasn't the iPhone 1 aluminum on the back? The iPad is the same anodized silver too. They have experience. I've also have seen mistakes or bad anodization in my own professional experience that wear early. Kind of thinking this may be the case here, especially for the out of the box problems. I hope apple sorts this out. Could be a bad batch. HOWEVER, I've seen marks on both black and white phones, mostly on the bevels. Whether due to wear or scratches, it's less apparent on the white, BUT on the black, I can cover it up with a black sharpie. What will I do with the silver? Not much. So I will go black, and wait a tat for Apple to figure this out. I like black better. The scuff gates I've seen, well most all of them feel rough to my finger, so that is a scratch, not a chemical problem. Other scuffs are not so clearly understood to me. It is curious. Some hated the glass back due to scratching. Well aluminum is softer than glass. But glass will shatter, Al will dent and scratch. Steel is too heavy and has RF problems. The macs are made from Al, but they all have feet on the bottom so they don't scrape on the desk; phones don't have feet. I think what is needed on the phone is just a screen protector on the metal back, or slim bumper feet to raise it off of surfaces. That would protect the matte back, the glass, and the bottom bevel edge from normal wear when laying on various table surfaces ( that are metal or have sand on them). The iPads could use the same. Just a thought. A good anodization will last a reasonably long time, if no mgfr for errors are found. But scratches are something else and a fact of life. At least a black matte sharpie on the metal back will cover them up well. I like character but not on my phones. I would go white but I like the display better with a black border.