Mozilla Thunderbird address book
The Mozilla Thunderbird address book is stored in
history.mab files in your profile directory (a system specific location). You can also create additional address books within Thunderbird that get saved in other .mab files, but copying files of that format into the directory won't work properly because only the two specifically noted filenames will be found automatically; others are known only if created or imported within the program.
The format is the widely disliked Mork format, disowned even by its creator, for which few third-party developers wish to figure out how to do any kind of support; you're best off using Thunderbird's import and export features to get data between this and other more widely supported formats.