I found this Kodak Super 8 cartridge in a box with old photos. Has the film been used or not? If the second picture doesn't tell, how can I find out? It would be nice to know so that I know if I should try to have it processed or not.
It's either unexposed or partially exposed.
From tmtv.net's page on old movie film processing, if the roll was completely exposed, you'd see this:
"EXPOSED" meaning the film has been shot and ready for processing (developing). DO NOT REMOVE OR ATTEMPT TO OPEN THE CARTRIDGE.
If it does not say "exposed" it was either removed from the Super 8 camera before it was finished or it is a new roll and not exposed, however new rolls are usually in their original sealed package in an unopened box.
While color Kodachrome processing was officially discontinued at the end of 2010, you may still find a lab that can process it as a black and white negative, like this one.
Super 8 movie film remains in use. However, the film inside your cassette is Kodak Kodachrome. This is a discontinued color film that required special processing. Sorry to report that the special process is no longer available. You are strongly advised not to use this film. You might choose to keep it and put it on display or donate it to a museum. I don't believe anyone will pay you so donate.
You actually can have this developed. My husband and I are in the same boat. We also are wondering if the cartridge is processed or unprocessed. But, there is a company called Film Rescue that can develop this. It just cannot be developed in color, only black and white.