Annodizing is only the color.. they take the regular metal and add a electrical charge to it and the color is hardened to it.. its really popular in motorcycle parts and car parts.. and such..
although, i would imagine its capable of wearing off from constant rubbing..
aslo fades in direct sunlight over long periods of time..
http://en.wikipedia.org/wiki/Anodizing
here is a pic orf my motorcycle with some anodized metal parts, bolts and screws are common too..
chris
the blue and the gold in the first picture are anodized aluminum..
and the gold break and clutch levers are anodized gold in the second pic..