In my defence of this request, I will reference Isabelle Théry-Parisot's "The use of bone as fuel during the palaeolithic, experimental study of bone combustible properties" (and through that reference also the many citations referenced therein), which shows that bone was actually widely used as fuel for stronger fires in the Paleolithic era, with wood used to initiate the fire and after it got up to temperature where green wood would also burn, bone was added as a long-burning fuel to keep the fire going, and going stronger.

The outer bone was more resistant to fire and is the predominant material left behind as charred bone recovered from Paleolithic-era fire pits, but with a mere 15% wood-by-mass compared to the humerus of an ox (Their smallest sample size listed as 4000g, so 600g wood), the bone was able to combust and then the fire was able to be maintained with bone material alone, and it was used primarily for light and heat required for production, as with curing of hides, or drying.

As such, I'd like to request that bone be usable as material to refuel fires and fuelable structures, but cannot be used to build fire-using buildings initially (representing that the bone is added to an active fire rather than being used as the initial fuel), to represent the cancellous bone material being used to keep the fire going, with a brighter, larger, hotter flame than what wood alone would achieve, while also producing bone ash as byproduct.

However, maintaining bones used in structures as being non-flammable is also accurate, as the compact bone structure that makes up the majority of the outer bone mass is non-flammable, and will instead simply char and degrade, the latter primarily due to thermal warping, as with rock cutting using fire to induce thermal shock as was done in ancient Rome and Egypt.

So, with all this said, the formal request is as such: The use of bone to refuel fires and combustion-based fuel sources, *but not be usable to initiate them on their own* (eg. a bone torch or bone fireplace or fueled stove would still require some wood for the initial recipe), while retaining the nonflammability of bone structures as is currently the case.