Rotary Air Blast (RAB)
Rotary Air Blast (RAB) is the simplest and most economical technique and is typically the first step in a mineral exploration project. Performed by drilling a borehole of about 3 to 3 1/2 inches, using either a drag bit or a down-hole hammer, the soil and rock samples are evacuated by air through the annulus between the drill steel and borehole wall. This inexpensive technique allows you to obtain a good idea of a site's mineral potential. This method can be useful in preliminary exploration however, to obtain soil and rock samples that are not contaminated by the borehole wall above the sample depth, we need to rely on diamond core drilling or reverse circulation techniques.