Blue gum also known as Bloekom, can burn very hot and for a long period of time. This is an invasive alien species, native to Australia. I is a very thirsty species, deprive surrounding vegetation of necessary water and minerals.
Blue Gum is a dense wood and does not burn for as long as the other hardwoods, but although it is known to burn very hot. A Slightly damp blue gum would work great if you are aiming for the longevity of the fire over the heat factor.
