When to choose RC over diamond core for greenfield exploration

Both reverse-circulation (RC) and diamond core drilling are valid first picks for greenfield mineral exploration. Picking between them is a question of cost-per-metre, sample fidelity, and how much you intend to drill before you commit to a deposit.

Sample fidelity

Diamond core preserves the full geological record - rock structure, alteration halos, vein orientations, and grade trends. RC delivers chip samples carried to surface by compressed air. The chips are useful for grade estimation but lose structural information.

If your exploration target depends on understanding orebody geometry - strike, dip, continuity - core is the right tool. If you're confirming grade across a broad footprint before deciding where to drill core, RC is faster and cheaper per metre.

Cost per metre

RC drilling typically runs at one-third to one-half the cost per metre of diamond core for the same hole diameter, because it sacrifices the slower, more controlled cutting action that produces intact core.

Decision matrix

• Scout drilling, broad grid coverage, grade confirmation → RC.
• Resource definition, geotechnical study, metallurgical sampling → Core.
• Mixed programme, deep targets → RC for the upper section, then switch to core at the target depth.
• Budget-constrained programmes that need quick decisions → RC.
• Reserve estimation that will be defended to investors → Core.

RC tells you where to drill core. Core tells you what to do next.

What Velson builds

Velson manufactures both - the EDC Core Drill (NQ/HQ/PQ capacities to 2,200 m) and the RC Drill (114–155 mm to 300 m). They can be deployed independently or as a programme pair. Service support is the same crew for both rigs, simplifying field operations.