Copper Drilling: RC vs Diamond vs Aircore With Costs

For copper, reverse circulation (RC) drilling is the usual first tool for testing a target quickly, and diamond core drilling is what you use to learn the rock. In the two 2026 filings used here the pattern differs by project: at Karakubis shallow percussion holes screened cover and RC holes with core tails tested targets, while at Haib core holes mostly 300 to 400 m deep define the deposit. One drilling-glossary rate card lists base rates of about $30 to $55 per metre for RC and $110 to $250 for diamond, and says the all-in price is often double the base rate (Novo Resources glossary, read October 2026). This page shows which method fits porphyry and sediment-hosted copper, how deep and how close the holes go, what filed budgets say per metre, and how results are reported.

RC, diamond and aircore drilling for copper: which method when

Four methods cover most copper exploration. They differ in what comes out of the hole, how deep they go and what a metre costs. The drilling-rig types themselves, with rig sizes and sample trade-offs, are covered in our guide to exploration drilling rigs; here the focus is on copper.

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Base rate per metre by drilling method

Dollars per metre, average base rate before extras (currency as given by the source)

• Rotary air blast (RAB): a cheap, quick method that uses a rotating blade bit on single-tube rods. Sample quality is generally poorer because chips can be contaminated on the way up. It suits the earliest stage of project evaluation (Novo Resources glossary).
• Aircore: a triple-blade bit on double-tube rods, so the sample returns inside the rods and mixes less with the hole wall. It only bores unconsolidated or weathered ground and is limited by air pressure, so it is a first-pass tool.
• Reverse circulation (RC): compressed air drives a hammer at the bottom of the hole and carries chips up an inner tube to a cyclone at the surface. It gives more reliably clean samples than RAB or aircore at a higher cost, so it is common at advanced exploration stages. A drilling-equipment maker notes that RC is probably the most common exploration method and is popular in South America and Australia (Dando Drilling, 2016).
• Diamond core: a rotating bit set with industrial diamonds cuts a solid cylinder of rock. Core diameter runs from 27 mm (AQ) to 85 mm (PQ), and 50 mm (NQ) is the most common in exploration. It is the most expensive method on average and gives the most representative sample, which is why it is used at advanced stages.

The glossary does not state a currency or a date for these rates, so treat them as a rough guide read in October 2026. Speed explains much of the gap. The same Dando note gives an illustration of about 30 m on a good 12-hour core shift against about 150 m with RC. Hammer RAB costs roughly 30% more than blade RAB, and the glossary adds that RC and diamond rates both rise with depth, and core rates rise with core diameter.

A very common copper programme combines the two. The RC rig drills the top part of the hole fast, and a core tail finishes it where the ground is fresh and the rock needs to be seen. The JORC Code asks companies to say which they used: its Table 1 asks for the drill type (core, reverse circulation, open-hole hammer, rotary air blast, auger, sonic) and details such as core diameter and the depth of any diamond tail (JORC Code, 2012 edition).

The choice also sets how samples are cut. The Canadian Institute of Mining guidelines say core can be sampled to a vein or altered interval, while samples from RC and other rotary holes are typically a constant length (CIM Mineral Exploration Best Practice Guidelines, 2018). For the market behind this drilling, see our notes on copper and iron ore and the largest copper producers.

Drilling a porphyry copper deposit: depths and spacing

Porphyry copper deposits are large, low-grade bodies of copper sulphide minerals around an intrusion. Because they are big, the drill programme is big: you need many metres to show continuity across a deposit that may be hundreds of metres wide. Our guide to porphyry copper deposits covers the geology; the drilling pattern is best shown by one recent, fully published example.

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Copper hole lengths in two filed reports

Metres per hole

Haib, in southern Namibia, is a porphyry copper project near the South African border. Its March 2026 technical report (MSA Group for Koryx Copper, under NI 43-101) describes three layers of drilling:

• Discovery-era grid. In the 1970s RTZ drilled 120 diamond holes on a 150 m square grid, 45,903 m in total. Holes were generally 300 to 400 m deep and used N or B core sizes.
• Infill. The denser drilling that supports the Indicated resource sits on an irregular grid of typically 40 to 80 m. The Inferred resource sits where spacing is about 150 m along and across strike. The block model uses 50 m by 50 m cells, about one third of the average drill spacing.
• Hole length. Across the whole database, holes range from 18 m to 843 m and average 320 m. Vertical holes suit the gently dipping south-east zone, while angled holes suit the steeper north-west zone.

The scale of the programme follows from the deposit size. At a 0.15% copper cut-off (the lowest grade the report treats as worth mining, in an open pit), the Indicated resource is 744 million tonnes at 0.28% copper. For the 2026 pre-feasibility work the company planned 55,000 m of infill drilling, followed by 20,000 m of deeper and step-out drilling, with six rigs on site and four more added in the fourth quarter of 2025 (MSA Group, Haib NI 43-101 report, March 2026).

Why oxide and leached caps change the plan

Many porphyry deposits have a weathered top. The U.S. Geological Survey porphyry model notes that early exploration focused on copper oxide in weathered outcrops, and that drilling often missed the higher-grade chalcocite blankets (secondary copper sulphide) sitting under thoroughly leached outcrops. Many porphyry copper deposits were found by drilling through leached cap (USGS Scientific Investigations Report 2010-5070-B). The practical lesson is to design holes that go through the oxide and leached zone into fresh rock rather than stopping at the first low assay. At Haib the resource table separates oxide and transitional material from sulphide, and the 1970s core was assayed for both total copper and acid-soluble copper, because the oxide part is treated differently.

Drilling sediment-hosted copper: RC pre-collars and core tails

Sediment-hosted copper forms in layers of reduced rock, so the target is often a thin, flat-lying bed rather than a big round body. That changes the drilling: the question is which horizon you hit and how thick it is. The USGS sediment-hosted stratabound copper model describes how the Chimiwungo North orebody at Lumwana, Zambia, was found in 2004 by drill-testing an induced-polarization chargeability anomaly, after which more than 150 square kilometres of IP were surveyed and 27 anomalies were identified. Two of these (Kanga and Kababisa) had been drill-tested by June 2008, and both intersected significant copper sulphide (USGS Scientific Investigations Report 2010-5070-M).

Two filed examples show the typical sequence.

• Kakula, Democratic Republic of the Congo. In June 2016 Ivanhoe Mines reported seven rigs working with two more on standby, and 25,000 m of drilling due to finish in the third quarter of 2016. Reported intercepts such as 393.00 to 412.00 m (downhole) show how deep the flat-lying bed sits. Sawn core was sampled at nominal 1 m intervals (Ivanhoe Mines, 20 June 2016).
• Karakubis, Kalahari Copper Belt, Botswana. The SLR technical report dated 9 February 2026 records an earlier mix of methods: shallow percussion and RAB holes (about 1,600 to 1,800 m in total; the report’s summary and its drilling chapter give slightly different counts), then RC holes, then four holes with RC pre-collars and diamond tails, 1,370.27 m in all. The RC part was drilled with an 8.5 inch down-the-hole hammer and switched to NQ core when water pressure got too high for the hammer to make progress. In 2024 the company completed seven diamond holes totalling 3,293.93 m, an average of about 471 m each (SLR Consulting, Karakubis NI 43-101 report, 2026).

The Karakubis case shows one reason programmes switch to core: when water pressure rose, the hammer could make no further progress and the hole had to continue with a core bit, so the geologist could log the beds and structures that place the next hole. For where these belts sit around the world, see our guide to where copper is found and the overview of copper deposit types.

Hole depth and spacing by project stage

There is no single spacing for copper. Spacing is chosen from how far the grade stays continuous, which the resource geologist measures with a variogram (a plot of how similar two samples are as they get further apart). The table below uses only spacings and depths from the filed reports above.

As a rule, spacing falls with each stage while the metres drilled climb sharply. The block model cell size at Haib (50 m) was set from the average spacing, which shows how closely drilling and resource modelling are linked. Core from the definition holes is also where metallurgical and density samples come from; our explainer on rock core samples shows how that core is logged, split and tested.

▶ Explains how satellite targets are ranked into a drill order. · 2:19

How much does copper exploration drilling cost per metre

Public per-metre prices are scarce because contractor rates sit in private contracts. Two sources are useful: rate cards that give a base rate, and technical reports that give a budgeted rate for a named project. Always check the currency and what is included.

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Haib 2026 drilling and assay budgets

C$ million, two programmes (55,000 m and 20,000 m)

US readers can convert with 1 m = 3.28 ft: the Haib drilling rate of C$263 per metre is about C$80 per foot. The Haib budget also implies one assay for every 2 m drilled (27,500 assays for 55,000 m in the first programme), so assays are a modest cost next to drilling: about C$1.35 million against C$14.47 million in the first programme.

What pushes the price up or down

• Depth. RC and diamond rates both rise with depth. A hole that must pass a water-bearing zone may need casing, mud or a switch from RC to core, as at Karakubis.
• Core size. Bigger core costs more per metre. PQ is chosen when more rock is needed for metallurgical testing.
• Remote access. Camp, fuel, water, helicopter time and mobilisation are often billed separately from the metre rate.
• Rig supply. A programme of 55,000 m, like Haib’s, needs several rigs on site at once, so tender early and read the standby and minimum-metres clauses.

Use the calculator below to turn your own quote into a programme budget. The defaults are round examples, not benchmarks; replace the rate with a written quote for your ground.

Which diamond core rig is easiest to move between sites

Ease of moving depends on the access as much as on rig weight, so match the rig to the pad. At Haib, the operator started with two track-mounted rigs, added two skid rigs in early 2025 to reach steeper valley sides, and from November 2025 added six man-portable rigs for the hardest-to-reach pads (MSA Group, Haib NI 43-101 report, March 2026). In snow country, contractors also use rigs that split into helicopter-liftable modules; ask each one for assembled and heaviest-module weights, the depth reached at your core size and whether depth falls with lighter rigs.

Weight can also decide the permit. In Ontario, for example, a drill above 150 kg assembled weight is a permit activity rather than a plan, according to the province’s exploration permit form as summarised in our Canada guide, which is one reason to ask contractors for assembled and module weights before you plan the season. Our guide to diamond drilling companies in Canada covers permits, ice roads and helicopter-supported programmes in more detail.

Questions to ask each contractor before you compare metre rates:

1. What is the assembled weight, and what is the heaviest module?
2. Does the rig need a road, a cleared pad or a helicopter pad, and how big is the pad?
3. What depth does it reach at NQ and at HQ core sizes?
4. Is mobilisation, camp and water priced in the rate or on top?
5. How many metres per shift does the crew expect in this rock, and what standby rate applies?

How copper drill results are reported

Drill results become public through a stock-exchange news release, and the format is set by rules. In Canada, section 3.3 of National Instrument 43-101 requires a company that discloses exploration information to give the location, number, type and spacing of samples, any drilling, sampling or recovery factors that could affect reliability, the analytical method and laboratory, the analytical values and widths, and the true width of the mineralised zone where it is known (NI 43-101 as published by the New Brunswick securities regulator, original 2005 text). Securities regulators have proposed a replacement rule that would also list each hole’s location, azimuth and dip and the depth of each sample interval (Canadian Securities Administrators request for comments, June 2025); check the in-force wording on the Ontario Securities Commission instrument page. In Australia the JORC Code uses a Table 1 checklist with sections for drilling techniques, sample recovery, logging and sub-sampling (JORC Code, 2012 edition). For example, Table 1 asks whether core was cut or sawn and whether half, quarter or all of it was taken.

In practice, a copper drill result reads like this:

• Downhole length versus true width. A hole that cuts a dipping bed at an angle is longer than the bed is thick. Ivanhoe’s Kakula releases give the true width and also the downhole interval for each intercept.
• Cut-off grade. Intercepts are quoted above a stated copper grade. The 2016 Kakula release shows composites at 1%, 2%, 2.5% and 3% copper. The Haib resource uses a 0.15% copper cut-off and caps extreme assays at 0.8% copper in the 0.2% copper grade-shell domains.
• Copper equivalent. When molybdenum, gold or silver add value, results may also be shown as copper equivalent (CuEq). Haib reports CuEq next to copper, molybdenum and gold grade; the equivalent depends on price and recovery assumptions that should be stated.
• Oxide and sulphide. Acid-soluble copper assays separate oxide from sulphide copper, which matters for processing route.
• Quality control. Ivanhoe’s release states that blanks and standards are inserted at 5% in the XRF stream and that copper assays were done by mixed-acid digestion with an ICP finish at an accredited laboratory. Portable XRF results are shown as indicative only.

When you read a drill release, check three things: whether the width is true or downhole, which cut-off was used, and whether the hole was surveyed (otherwise azimuth and dip are planned values, not measured ones).

Screening ground before the first hole

A drill hole tests one small column of rock, so most of the saving is in choosing where it goes. Public surveys, geophysics and satellite imagery narrow the search first. Satellite data cannot see copper at depth, but it can map iron-oxide staining, clay and mica alteration and the faults that often control copper systems, which helps a consultant rank targets and decide which holes go first. Farmonaut offers satellite-based mineral target mapping that uses a licence boundary as input; the results are exploration targets that sit ahead of any drilling and resource estimate.

The same logic applies to a programme already under way: keep collars, logs and results in one place so each new hole is planned against what the last one showed. The short video below shows how a mineral management system keeps those records together.

▶ Shows how a mineral management system keeps maps, samples and targets in one place. · 3:21

Frequently asked questions

What is the best way to drill for copper?

There is no single best method. RC is quickest for testing targets, aircore and RAB suit shallow screening, and diamond core is needed when you must see textures, measure structure or collect metallurgical samples. The Karakubis programmes combined percussion, RC and RC pre-collars with core tails, while the Haib deposit was defined by diamond core.

What is an advanced copper drill?

The term is not a standard rig class. In practice it means a rig matched to the job: an RC rig for fast target testing, a core rig for deeper holes, or an RC pre-collar followed by a diamond tail, as used at Karakubis. The JORC Code also lists sonic drilling as a drill type.

Can copper mine diamond, or are diamonds involved in copper drilling?

A copper mine does not produce diamonds. In diamond drilling the bit is impregnated with industrial diamonds, which are hard enough to cut a cylinder of rock; the diamonds are in the tool, not the ground (Novo Resources glossary).

How deep do copper exploration holes go?

It depends on the deposit style. At Haib the database holes range from 18 m to 843 m and average 320 m, and the 1970s grid holes were 300 to 400 m. At Karakubis the 2024 core holes averaged about 471 m. Reported Kakula intercepts lie roughly 265 to 412 m downhole.

How far apart are the drill holes?

It depends on the stage. At Haib the first grid was 150 m, the Indicated resource sits on typically 40 to 80 m spacing, and one high-grade section was drilled at 25 m. The spacing is set from how far grade stays continuous.

How much does RC drilling cost per metre compared with diamond?

One rate card gives about $30 to $55 per metre for RC and $110 to $250 for diamond (base rates; read October 2026), so diamond base rates run roughly four times RC. Filed budgets fall inside the diamond range rather than above it: Haib budgets C$263 per metre (about US$192 at the report’s exchange rates; March 2026) and Karakubis US$225 per metre (February 2026). The reports do not say what each figure includes, so compare them with care.

Why is diamond drilling slower than RC?

Dando says core drilling is slow and costly because of core bits, drilling additives, fuel and labour, and the core must be pulled and laid out in trays (Novo Resources glossary). Dando gives an example of about 30 m per good 12-hour shift against about 150 m with RC.

Which diamond core drilling system is easiest to mobilise between sites?

There is no single answer. At Haib, man-portable rigs and skid rigs were used for the hardest-to-reach pads, and track-mounted rigs elsewhere (March 2026 report). Ask contractors for assembled and heaviest-module weights and the depth each reaches at your core size. Ask contractors for assembled and heaviest-module weights and the depth each reaches at your core size.

What do drill results mean for copper grade?

A result gives the copper grade (as % Cu) over an interval, with the width and cut-off used. Read the true width, the cut-off, the assay method and the QA/QC steps before comparing two releases.

Does a good drill hole prove a deposit?

No. One hole shows one column of rock. A resource needs enough closely spaced holes for a qualified person to show grade continuity, which is why Haib’s classification depends on spacing. This page is general information; check the rules in your jurisdiction and your own licence conditions before drilling.