The effect of surface texture on the determination of the surface hardness of rock using the schmidt hammer

The Schmidt hammer is employed by geomorphologists as a convenient field instrument for measuring the hardness of rock surfaces. Field trials indicate that the readings obtained are a function of not only the hardness of the surfaces but also their texture. Smooth planar surfaces give much higher readings than rough or irregular surfaces. This makes interpretation of the results particularly difficult when the hammer is used to measure the hardness of natural rock surfaces that have been roughened by weathering.