air core vs diamond drill and rc drilling, page-2

Diamond drilling is the ducks nuts as it provides the geologist with the best structural information and visuals displaying the setting of the gold. generally diamond drilling can reach depths of 1000m +, but is slow generally 50m per 12 hour shift. the downside is that it's expensive ($300/m)

Rc drilling is the next best: it's much faster than DD. cheaper but produces chips which are lifted out of the hole with air pressure. it assay costs are cheaper because most companies send me composite samples of multiple metres (usually 6). and if any sniffs of gold come back they will send the individual metres for assay. RC drill rigs are usually limited to 500m max depending on how much water is in the hole.

AC is the cheapest $50ish\m, the fastest and the most limited in its capability. as you said, great for scoping. AC is limited to drilling through cover sequences (younger waste sands or rock) into the soft weathered oxide rock. past this point the rig can't drill any further called "drilling to refusal".

what type of rig you use depends on your budget, the ground you are drilling, the depth of target and the desired result.

hope this helps!