Starting with Firefox version 49, Firefox requires Mac OS X 10.9 (Mavericks) or higher. Visit this Apple Support page to find your Mac OS version.
The Firefox version 48 release in August 2016 will be the last Firefox version to receive new feature or security updates on OS X systems that are no longer supported by Apple: OS X 10.6, 10.7 and 10.8. Starting with the Firefox version 49 release in September 2016, Firefox is no longer supported on OS X systems below 10.9. Mac OS X Snow Leopard Free Download DMG 10.6.3 Clean Rip. It is final bootable OS X Snow Leopard Install DVD 10.6.3 DMG for Clean OS X Reinstall. If you need to purchase Mac OS X 10.6 Snow Leopard, you may order it from this page. The current version of the Mac operating system is macOS Sierra. Old Version of Firefox for Mac for Mac OS X 1.
If you're using an outdated version of Firefox on Mac OS X 10.8 (Mountain Lion) or earlier, the only way you can update Firefox to a secure version is to upgrade your Mac OS to a version that Apple supports. Visit this Apple Support page to learn more about upgrading your Mac.
Mozilla Firefox For Mac Os X 10.6.8
While insecure versions of Firefox will continue to work on OS X 10.8 and earlier, using an up-to-date version of Firefox on a supported version of Mac OS will provide you with the best and safest user experience.