I recently scored a pickup load of silver maple that was dropped to make room for a parking lot. I wanted to compare it with the other wood currently in my pile (a mix of western larch/tamarack, ponderosa pine, cherry and tulip poplar. I split it up into smallish splits, about 4 inches per side, and speed dried some of it next to my firepit over a couple of days. I used similar sized splits of each of the other woods I have, and built several fires with the same load size, and I found that the silver maple keeps the coals longer than even the cherry and tamarack. The thing I don't understand is WHY it did this. The BTU ratings I've seen in several websites put it lower than the tamarack and cherry, and only slightly better than the pine. What characteristic of the wood causes this to be the case, as far as burning time and coaling time are concerned?