Reverse Circulation (RC) –produces a hole size Ø 140mm and is generally faster than diamond core drilling and generally produces better samples than rotary air blast (RAB) drilling. Reverse Circulation (RC) is more expensive than RAB and Air-core drilling but less expensive than Core (DD) drilling.

Reverse Circulation (RC) drilling produces rock chips rather than a Core sample. The RC method produces sample from depth by pulverizing rock with compressed air and a percussive hammer and returns it to surface through an inner tube and collects it through a cyclone then into a sample bag.