Hardwood

The standard by which hardwoods are tested and rated is called the Janka Hardness Test.  This test measures the pounds per square inch required to embed a 0.444 inch steel ball to half its diameter in the wood.  It is an indicator of the ability of a wood species to withstand denting.

Note that the scale is linear.  So a wood with a hardness of 1800 is twice as hard as a wood with a hardness of 900.

Janka Test

Janka Test