At 10:39 AM 6/20/01 -0700, Fred wrote: I had thought it was common knowledge, the reflective layer in many CDs is sputtered aluminum. When exposed to oxygen (as can happen when oxygen migrates through the plastic or the plastic is cracked) the Aluminum oxidizes and turns black. It does look a bit like a fungus but only because it tends to follow the grain pattern in the deposited aluminum. Aluminum-oxide is black and quite hard actually. I've seen several examples of this in "real life" and while I have never seen the process to actually _remove_ Aluminum from the disk it is conceivable that the Al02 would form a different crystal matrix and thus change its orientation relative to the original sputtering. That could leave 'gaps' where the original reflective layer was. So folks to don't understand chemistry invent the 'fungus' idea and off it goes into urban legend-dom. --Chuck