When searching for , users often misunderstand the file format. Apple never officially distributed OS X as an ISO. Officially, Mountain Lion came as an APP file (downloaded from the Mac App Store) or a DMG (Disk Image). So why do people want an ISO?
to convert the DMG into a bootable ISO for a virtual machine? Mac OS X Mountain Lion Installer - Apple Support
: The installer file contains a hidden disk image called InstallESD.dmg .