I try to give as accurate view about drilling methods and cost...

I try to give as accurate view about drilling methods and cost as I can.

AC is the cheapest - drilling 1 meter costs about 35$. Rig needs water supply, which is usually stored in support truck water tank and hose is connected with rig. AC rig usually runs with 350 psi and is used to drill soft ground until you reach hard rock, scratch it a little bit (Bit can't go through hard rock) and get your final sample. AC is usually used first to get some sort of idea about mineral grade and shallowness of the hole until hard rock. AC rig consumes average 300-400 litres of diesel per shift and rods are 3 m long. Crew usually gets bonus per driller meter after 400m and higher bonus after 600. What they average drill per shift is 300-400m. But I've witnessed also 1000m shift.

If lab test results show promising mineral grade, then company extends the program and RC rig joins the party. It's now more complex drilling. During the drilling, drill rig, support truck and air truck are used, so 1 extra vehicle. RC drill rig runs with 6m rods and depends on the program (if drilling is slow), all equipment together can consume up to 1200 l diesel (drill rig + auxillary and booster on air truck). Drill rig produces somewhere 500-600 psi and air truck can produce somewhere 350-400 psi. Air truck compression hose and air hose are connected to drill rig. Samples are also taken after every meter and geos can ask to clean cyclon in the middle of the hole to minimize contamination. RC rig is used to get more accurate sample and drill hard rock to test mineralisation. RC rig drilled meter costs about 70$ and crew get bonus per meter after 200m and higher bonus after 300m. Average RC rig drill 150-250m per shift but I have witnessed 600m shift.

Diamond drill rig is final stage of drilling and it gives pretty much exact overview about the ground and grade. Diamond drill rig uses a massive amount of water - thousands and thousands litres per shift, but Im not going too deep in the method, why is that. Rods used in diamond drilling are 3m long (but can make even longer gear when mounting 2 rods together), but diameter of the rods varies. Underground, commonly used rods are BQ, NQ and HQ, where BQ rods have shortest diameter and HQ longer diameter. On the surface, rods with longer diameter than HQ rods are used. Additional to more accurate sample, diamond drill rig also gives information about ground conditions. If the samples (core) are half meter or meters long, then ground is really hard and solid and thats good news for client, because when opening mine, it gives good solid and stable conditions, especially underground, where jumbo op can drill rock bolts securely and prevent ground from collapsing. If core is broken, then mine ground conditions will be very poor. Diamond drill rig cost per meter is about 200$ and can go 20-30% higher after 300m or so, but depends on the company. Ardea 500m diamond drill hole did cost 112 000$, so pretty close.

All the meters and costs are approximate assumptions and very few people have actual clue, how much every drill meter costs to client. So definitely don't take this information as 100% gold.

So, DDTRH, to Your final question. Drilling clay can be challenging, because of its texture. Different drill additives/lubes are used to help clay move to cyclon and finally to bucket or bag, whatever is used by the time. Drilling clay, drill rig can't be pushed too hard, becuase clay tends to block hammer or even cyclon hose. But clay definitely isn't biggest challenge in drilling, I would say average and driller shouldn't have big problems drilling clay. Worst ground condition is running sand. But finally, sorry mate, Im not competent to share my point of view about clay and processing part. But ground conditions are not surprise for JC and Ardea and I consider that as minor obstacle. JV is fully aware of the ground and all the experience and knowledge will shared among ea. JC wouldn't be on the board if clay would be obstacle and a lot of ore wouldn't be possible to extract.