There's a couple different trees that are called "ironwood". We have one around here, whose proper name is American Hophornbeam. Also called "musclewood" because of its strange, corded appearance. Extremely hard and resistant to splitting. Good for tool handles, if you have the patience to shape it. There's another "ironwood" from down in the tip of Florida and the islands there, called Lignum Vitae; the tree of life. It's so dense that it won't float! Beautiful stuff, though scary expensive nowadays.