i'v not heard that about lightning making the wood fireproof, but there is an actual tree whose wood wont burn. its called a Black Poplar, and is massively rare. (apparently years ago the farmers cut down all the female trees as the seeds (apparently like dandelion fluff) would fall and ruin all the crops. im not sure how true this.) we had two on the farm, one died and we cut it down, seasoned it for years and it still wouldnt burn AT ALL! apparently they used to use the wood in ships?
well, there is your useful bit of information for the day guys! =)