to find them ? >finder >Go >"Go to folder" > type ~/library >application support >minecraft >screenshots
Are you on OS X Mountain Lion/Lion or OS X Snow Leopard/Leopard? If you are on Lion, an answer for how to find your minecraft folder can be found here: http://empireminecraft.com/threads/help-meh-mac-minecraft-stuff.26214/
Then you checked the wrong library. For this example I will use the profile name bob. Go to Bob Library Application support Minecraft Screenshots If you don't have a minecraft folder, you did not follow these directions exactly. If the folder named library does not have three columns on it, it is not the right library folder. Look in the library folder that has three columns on it. After that, for easy access, right click the folder labeled "Minecraft" and click create alias. This will be named "Alias of Minecraft" It will be placed on your desktop.
Click your desktop background Go to Finder up on the top of your screen Go to "Go" Click "Go to folder" Enter: ~/Library/Application Support/minecraft Click Screenshot folder ?
Ah! I know your pain. I had this issue as well and my fix was as follows. Head on over to finder (be on your desktop). Click on "Go" Now you will see a list of things there. Hold down "option" key. You will see "Library" magically appear. Click that Then "application support" folder Then "minecraft" folder is there! BOOM! Fireworks! Hope that does it for you