Desert ironwood, which is so dense that it does not float on water.

Desert Ironwood grows in the southern states of the USA and in northern Mexico in desert landscapes. It is very hard, has a high density and therefore absorbs very little water. It is used for knife handles and is also popular for stocks of handguns. Due to its high hardness, it is more difficult to work with than other types of wood. It is classified as one of the most exclusive types of wood. Knives with handles made from this wood are sold at higher prices. As it is a protected species, only licensed individuals are permitted to harvest and trade this wood. Only dead trees may be harvested.

A little about the Olneya tesota tree (shrub)

One of the most important and oldest plants in the Sonoran Desert. Although its extremely dense wood makes standard tree-ring dating difficult, it is estimated that the tree can live for almost 800 years!  The tree acts as a host plant, its canopy providing ideal shelter and nutrients for many other plants, including the Saguaro cactus.  Its role in the desert is considered so important that the Ironwood tree has been a protected species in Arizona since the 1970s. Ironwood trees are very thorny.  In late spring, they produce beautiful pale pink, pea-like flowers and provide an excellent habitat for wildlife.