That;s the good stuff. People don't realize it grows in the US. Same as what used to be called "cuban" mahogany (swietenia mahogani). But i think it's protected. I've gotten windfalls sourced for government work that were in the size you mention, but thicker. It's also available from some pacific islands where the seed pods were borne, and the forest is now managed for income. That family tends to sell it by the ounce, more or less though they have great huge planks.
As Grey Ghost noted, it's not particularly dense or heavy, about like Walnut or cherry. Certainly not as hard as maple. It's one of the softest woods we use for complex floors. Swietenia mahogani tends to run denser and better texture than swietenia macrophyla, which is the current "true" mahogany of trade. Then again, mahogany's appearance and characteristics such as density and texture are maybe more prone to the local environment in which the tree grew than some woods.
smt