There are five open source icon sets built in to Blocs, you can easily use any of them in your designs.
The Icon Manager
The Icon Manager lets you quickly and easily navigate through hundreds of pre-installed icons. The navigation within the Icon Manager has two distinctive markers that are always displayed. The dot marker indicates the icon set that the current icon Bric is using and the highlighted tab indicates the icon set that is currently being browsed.
When you place an icon Bric into your design or use one of the pre-made Blocs that contains an icon, the icon will already be set. To replace an icon Bric’s icon, simply double click it or if the icon is already active click the preview thumb from the sidebar icon inspector options. This will open the Icon Manager, from here you can search and select an icon that you wish to use. Blocs comes with 5 popular icon web fonts pre-installed.