Anodizing as utilized on firearms is sulphuric anodizing that has been dyed black, it is approximately .0002" (two ten thousandths). It is a controlled oxidation similar to gun bluing (black oxide), its main function is to prevent further uncontrolled oxidation. It provides some protection from abraision though this is limited to its minimal depth, I would hesitate to call it ceramic though. Hard coat anodizing is another matter, it provides much more surface hardness and therefore resistance to attack from hostile environments. The drawback to hardcoat anodize is increased cost vs. sulphuric anodize, also it cannot be dyed the range of colors that sulphuric anodize can.
