Could have been any of a number of Eucalypts. They're all hardwoods, and remarkably tough. I'd suggest Jarrah because it has the property of being very workable while fresh, but hardening to a consistency that resists almost anything once it dries out. (The sleepers for much of the London Underground were originally made of Jarrah. Back in the 1980's they surveyed many of the lines, intending to replace them, as they were then about 120 years old. In most cases, they left the original sleepers in place - no rot, no damage, little wear!)