An N Type Schmidt hammer was used to measure the rebound of a
spring-loaded mass impacted against the surface of rock outcrops.
Referring to the Brown (1981) conversion chart, we applied the
rebound value to obtain uniaxial compressive strength.
In the field, we measured the number of discontinuities in the unit
column of rock outcrops and calculated the volumetric joint count ( Jv)
by the equation