Due to the Java-based development system and inability to build C/C++ apps, the full Firefox browser will not be available on the Blackberry OS. And may be once there was a build for Blackberry. But it is a dead project for technical issues may be.

The BackBerry OS's like BlackBerry 10 and the older BlackBerry Tablet OS for PlayBook is based on QNX. Once long ago you could build Firefox for QNX but support for QNX has long been removed from the Mozilla source tree.

Mozilla only has Firefox for desktop Windows, Mac OSX, Linux and the mobile Firefox for Android 2.3+. There is also "Firefox OS" used on say some budget phones and certain new Panasomic Tv's. They also just recently started with a Firefox shell browser for iOS 8+.

There has been no development of a mobile browser from Mozilla for any BlackBerry OS or hardware.