RC drilling is effectively percussion drilling whereby the rock...

RC drilling is effectively percussion drilling whereby the rock mass is pulverised and the material is returned to the surface in the form of rock chips and collected in a cyclone which then allows for geological sampling at specific depth intervals. This method of drilling is very rapid (generally 30 m to 50 m depth per day) however sampling and rock mass logging is less precise. Diamond core drilling (NQ, HQ, PQ diameter) results in a continuous undisturbed rock mass sample which allows for far greater rock mass characterisation (geological and structural properties) with depth. The latter provides for an intact visual representation of the rock mass (and associated mineralogy). Diamond core production rates are generally of the order of 15 m to 30 m per day depending on drilling conditions. Typically contractors will drill through known overburden horizons with RC and switch to coring upon reaching a target horizon (often referred to as diamond core tail) to enhance productivity. It is also important to note that diamond coring is an integral method of investigation for geotechnical purposes (e.g to support design of mine pit, slope stability and associated ancillary infrastructure).