Where in the file system are iPhoto pictures located?
iPhoto Photos Location

iPhoto stores photos and meta-data in the user's home folder:

~/Pictures/iPhoto Library

Within this folder, the original photos are stored at:

~/Pictures/iPhoto Library/Masters

Bulk Copy with rsync

If the user name was friend, the rsync command to copy all the original photos to the local desktop would be:

rsync -ra '/Volumes/MacMini/Users/friend/Pictures/iPhoto Library/Masters' ~/Desktop