An interesting fact about most 'ironwood' woods is that they are so dense that their specific gravities exceed 1.0, so they will sink instead of float when put in water.

Examples of ironwoods that can be found in North America include American hornbeam, mesquite, desert ironwood, and leadwood. Leadwood (Krugiodendron ferreum) has a specific gravity of up to 1.42, making it the heaviest in the United States.

The heaviest wood in the world is black ironwood (Olea laurifolia) also known as South Afri, which can be found in the West Indes. It has a specific gravity of 1.49 and can weigh up to 93 pounds per foot.