Created on: April 25, 2013
Last updated: August 25, 2015
The most common reason a new drive will not mount to the Desktop is when it has not been properly formatted yet. You can use the built-in Disk Utility from OS X to accomplish this simple task. Please see the Apple document below for more information.
(Follow the first set of steps under "Erase a disk" near the top of the page.)
Another common reason a drive will not appear on the Desktop, is that sometimes the OS X Finder preferences have been set to not show mounted volumes on the Desktop. This is easily fixed.
1. Go to Finder > Preferences > General Tab
2. Make sure under "Show these items on the Desktop", the "Hard Drives" option is checked.