The following are the steps to formatting an USB drive within Mac OS X (Mountain Lion)
- From Finder, click on Go on the menu bar then click Utilities (or up arrow, Command, Shift, and the 'u' key).
- Select the USB drive and select the Erase tab:
- Select the Format you would like to use for the drive (MS-DOS(FAT) for cross-compatibility with Windows or Mac OS Extended (Journaled) for use on Mac OS X computers only)
- Once you've selected a format, click on Erase to format the drive.