To be more clearer the nokia uses Symbian OS and also has a ARMv6 type of cpu (not ARMv7) which also makes it not compatible even if it had Android 2.2+ anyways. https://wiki.mozilla.org/Mobile/Platforms Symbian

  We currently have no plans to develop a fullFirefox browser for the Symbian platform. See Mobile/Symbian for notes from an inactive project to port Firefox to Symbian. However, a future version of Firefox Home may be available for Symbian.

^Oh sure copy+paste a post of mine without credit.

Nokia is phasing out Symbian use and slowly getting into Windows mobile use on the upper and some mid range phones. This makes it even less likely to have a version for Symbian.

mobile Firefox is for devices with Android 2.1 and ARMv7 type of cpu.