OS9 IMG files-lost data?

Question

How many people have had problems using .IMG files (NDIF images) to transfer files from OS9 to OSX?
I've lost some important data because some of my .IMG files are apparently now missing their resource forks.  I didn't realize that files in OS9 were PHYSICALLY SPLIT into two parts on the actual disk. Of course, the very idea of doing such a thing is beyond absurd. Yet, i never had any problems transferring files in the past, even when using e.g. PC-formatted Zip disks, because both parts of the file were always there! The error when i try to mount the images now in OSX is:
The following disk images failed to mount
[filename] not recognized
Nor can i take the files back to my OS9 machine and mount them anymore, to my horror.
<Edited by host>

Answer 1

Yes, i probably used a Windows-formatted USB drive to transfer the files. Could have been FAt32.
The problem is, when you see a file (icon) e.g. on your Mac OS9 hard drive, and you copy it to a USB (flash) drive, and it shows up there, and then you open it from there (to make sure it copied okay), and it appears fine, the idea of there being an associated *invisible* file is totally inconceivable. It's insane that anyone would write a computer operating system that places *crucial* parts of a single file IN ANOTHER, *INVISIBLE* FILE. Yet, that seems to be what's going on here.
So, you copy that file (apparently) off to your other computer (OSX machine in this case), and assume everything is fine. Then some months later, you try to open (or mount) that file, on your OSX machine, and it doesn't work.
Is this data (in the .IMG) recoverable..? The .IMG image is of course an image file containing lots and lots of other, smaller files.