40d:Fire-safe

Fire-safe materials are building materials that cannot catch on fire. These include stone, glass, and metal. Wood is not a fire-safe material. Fire-safe materials are only required when the object is going to come into contact with extreme heat, such as near magma.

Flux materials, such as limestone blocks, which are burnt up in the purification of pig iron to produce steel, are considered fire-safe. It is perfectly fine to burn calcite as a flux making steel in a limestone furnace. Ice is also a fire-safe material... somehow. Constructions will never melt or burn, but natural ice walls/floors/ramps/stairs will.

Note that constructions (Wall, Floor, Ramp, Stairs) can never burn, regardless of what they're made of.

Not to be confused with magma-safe materials. Most fire-safe materials will still melt when in contact with magma.