Portable Hardness

Hardness is a material's resistance to penetration. In general, an indenter is pressed into the surface of the material to be tested under a specific load for a definite time interval, and a measurement is made of the size or depth of the indentation.
Hardness properties include such varied attributes as resistance to abrasives, resistance to plastic deformation, high modulus of elasticity, high yield point, high strength, absence of elastic damping, brittleness or lack of ductility.

originally found here:- http://www.ndtindia.org/portable-hardness.html