Font Awesome
             

fa-sort-desc · Unicode: f0de · Created: v2.0 · Categories: Web Application Icons · Aliases: fa-sort-up

After you get up and running, you can place Font Awesome icons just about anywhere with the <i> tag:

fa-sort-desc 
<i class="fa fa-sort-desc"></i> fa-sort-desc

Looking for more? Check out the examples.