The Granite Fire is used to keep your villagers warm and safe from predators; this fulfils a need in order to keep them carefree.
The Granite Fire takes 4 days, 12 hours to unlock, and 3 days to build. This requires 50 Granite blocks and a Granite Hammer.
The Granite Fire will burn for 8 hours, and requires 38 Oak planks and 2 Flint Shards to light it.
By adding 80 Oil canisters to the fire, the burn time can be extended by 12 hours.