There are in essence two basic types of exploration drills: those which produce small rock chips (RC, RAB and Air core) and others which produce solid core (cylindrical) samples, called DD (Diamond Drill).
a) RAB drilling
RAB drilling is used frequently in the mineral exploration industry - this tool is also known as a “down-the-hole” drill. The drill uses a pneumatic reciprocating piston-driven “hammer” to energetically drive a heavy drill bit into the rock.
b) Reverse Circulation Drilling
RC drilling is similar to air core drilling, in that the drill cuttings are returned to the surface inside the rods. The drilling mechanism is a pneumatic reciprocating piston known as a “hammer” driving a tungsten-steel drill bit. RC drilling ideally produces dry rock chips, as large air compressors dry the rock out ahead of the advancing drill bit.
c) Diamond Drilling
Diamond core drilling (exploration diamond drilling) utilizes an annular diamond-impregnated drill bit attached to the end of hollow drill rods to cut a cylindrical core of solid rock. It is it is mainly used in the mining industry to probe the contents of known ore deposits and alsopotential sites.