What does mold look like exactly.  Does anyone know of any helpful photos for paperbacks especially?  If there is discoloration on a spine or cover (HC) of course I wouldn't want it in the first place and wouldn't pass it on.  What about brownish spotty looking stains on the top of a paperback.  No where else.  Hasn't changed in years and does not go onto the page but simply on the outside top of the book. 

When I bring used books into the house I microwave them for 10 seconds.  (Except for metallic colored covers)  I read that this kills mold and book mites if there are any.  I've never had a problem with the mites and, as far as I know, with mold.  But having never seen any photos I don't know for sure.

Go to www.google.com

Click images.

type in: mold on books

the first two pictures are pretty much how it looks.

Sounds like yours might be foxing: http://tinyurl.com/2r6k3k

If in doubt, don't post it.  It's way too risky spreading mold to someone else's book collection.

If it hasn't spread in years and looks like copper colored "speckling", it's foxing.  Mold will spread, foxing is a result of the chemical composition in some papers during the manufacturing process.

There is also a spray type of remainder mark thats purple when it goes on but changes colors later. I cant remember what its called but it looks like foxing.

As best as I can tell from the pictures and certainly from the copper color and the location this is foxing. 

Thanks for the help.  I have books from my childhood that have this and I don't want to part with them.

But I have passed up a lot of good books at sales because of this. 

Do you all pass those books by as well, to be on the safe side??  (For your own library or for posting)