May 28, 2013, 5:59 PM — Here's how you can install the Sphere icons in Linux Mint 15.
1. Open a terminal window.
2. Type in the following commands then hit Enter after each.
sudo add-apt-repository ppa:noobslab/icons2
sudo apt-get update
sudo apt-get install sphere-icons
For more, see the original article at the link below.