Module 4: Reading Drill Result Announcements

Why this matters

Drill result announcements are where companies most actively shape perception. The headlines are often technically accurate but designed to obscure what an experienced reader would immediately spot.

Learning to read drill results properly is the single highest-leverage skill in junior mining investing. Get this right and you avoid 80% of the traps.

The standard format

A drill result announcement typically headlines an intercept like this:

"PRG02 returned 24m @ 3.5 g/t Au from 85m, including 6m @ 11.2 g/t Au from 92m"

You need to decode every part of that:

What's not in the headline:

These are usually in the JORC Table 1 appendix, which retail rarely reads. Read it.

Length-weighted vs grade-weighted

Headline grade is length-weighted:

weighted grade = Σ(interval_i × grade_i) / Σ(interval_i)

Example: 24m intercept made of:

Length-weighted = (18×1.0 + 6×11.0) / 24 = (18 + 66) / 24 = 3.5 g/t

Looks like a uniform 24m of 3.5 g/t mineralisation. Reality: 6m of bonanza surrounded by marginal halo. Whether you can mine that depends entirely on geometry, mining method, and selectivity.

Always read the "including" sub-intervals to see what's really there.

Down-hole length vs true width

Drilling is often angled to intersect mineralisation perpendicular (or as close as possible). The reported intercept is down-hole length — the actual length of drilled core.

True width is the actual thickness of the mineralised body measured perpendicular to its strike and dip.

If the hole is drilled at an angle to the mineralisation:

Companies are required to disclose true width or state it cannot be determined. When you see "true width estimated at ~70% of reported length", apply that mentally to all intercepts.

When the announcement says nothing about true width, check the long-section diagram (if provided) and figure it out yourself.

Gram-metres (g·m) — the universal currency

Professional analysts rank holes by gram-metres (or %·m for base metals):

g·m = grade × down-hole length

So 24m @ 3.5 g/t = 84 g·m

This single number lets you compare holes across different deposits, different widths, different grades.

Rough benchmarks for gold drill holes:

For copper porphyry: %·m equivalent (e.g., 200m @ 0.6% Cu = 120 %·m).

Use g·m to cut through the marketing. A "100m @ 0.5 g/t" intercept (50 g·m) is being sold as more impressive than "5m @ 12 g/t" (60 g·m), but the latter is actually a better hit — and far easier to mine.

Drilling-type taxonomy — what kind of hole are you looking at?

Not all drill holes have the same purpose, and the same intercept means very different things depending on what kind of drilling produced it. This is the most under-appreciated part of reading announcements properly.

Grade control drilling

Infill drilling

Step-out drilling (sometimes called "extension drilling")

Exploration drilling (greenfield / regional)

Why the distinction matters

The same announcement reading "drill program returns 30m @ 4 g/t Au" tells you completely different things depending on which type of drilling produced it:

The announcement headline rarely tells you which kind of drilling produced the intercept. The body and the supporting plan-view diagrams will. Read them.

A useful framing: ask "is this hole inside or outside the existing resource boundary?" If inside, treat it as routine confirmation. If outside, treat it as new information, and ask how far outside and in what direction.

Common cherry-picking and obfuscation patterns

1. "Up to" reporting in headlines

"Up to 45 g/t Au returned from drilling"

That's a single peak assay over a 1m sample interval. The actual intercept might be 1m @ 45 g/t with 19m of barren rock either side. Always look for the weighted intercept, not the peak assay.

2. Loose "includes" wrapping

A 50m parent intercept at 0.4 g/t with a 1m core at 12 g/t lets the company headline either:

Same hole, two stories. Both true. Neither tells you if the deposit has scale and grade together.

3. Composite reporting hiding internal waste

A reported "20m @ 2.0 g/t" intercept might actually be:

Composited, it averages 2.0 g/t and looks like a single zone. In reality, two separate thin lodes with waste between them. Mining selectively to avoid the waste is much more expensive.

Look at the assay table in the appendix. The granular metre-by-metre assays tell the truth.

4. No top-cut applied

A rogue 200 g/t assay in a single sample can lift a 30m intercept from 1.5 g/t to 8 g/t on paper. Best-practice resource estimation applies a top-cut (e.g., cap all assays at 30 g/t). Drill result announcements don't usually apply top-cuts because doing so kills the headline. Mentally cap any single-metre assay above ~5x the bulk grade.

5. Hole orientation games

A hole drilled subparallel to a vein system will produce huge down-hole intercepts that have small true widths. "100m @ 5 g/t" sounds amazing but if true width is 8m, it's a far less impressive hole.

6. Selective announcement timing

The good holes get headlined immediately. The poor holes from the same program get bundled into a quarterly months later, or never reported individually. Cross-reference the program's planned holes (in earlier announcements) against the holes that were actually reported on. If they drilled 30 holes and you've only seen results from 12, the other 18 weren't great.

7. Mislabelling the drilling type

A subset of the prior issue. Companies sometimes describe routine infill drilling as if it were step-out or discovery, hoping the reader doesn't check the plan view. The plan-view diagram will show whether holes are inside or outside the existing resource shell. If the diagram is omitted or unclear, that's a flag.

Headline vs body — the discipline

Most retail read the headline of a drill announcement and stop. That's the trap. The body of the announcement contains the qualifications, the what-isn't-said, and frequently the actual story.

What to read in the body, in order

  1. The intercept table — every reported intercept with hole ID, from-to depths, length, grade, and (ideally) true width. Compare reported holes against the program plan announced earlier — what holes are missing?
  2. The methodology / collar table — hole positions, dips, azimuths. Lets you reconstruct geometry vs true width.
  3. The geological description — does the company describe the rock type, structural setting, alteration? Vague descriptions are a flag.
  4. The plan view and long-section diagrams — where are the holes in space? Are they inside or outside prior drilling? In what direction does the resource grow?
  5. The forward plan section — what does the company say about next steps, next drilling, next assays? This is where catalysts get telegraphed.
  6. The JORC Table 1 appendix — sampling, sample preparation, QA/QC, lab procedures, top-cut treatment, density assumptions.

The "no headline" tell

Sometimes a company drills a program, waits, and then publishes results in a quarterly activities report rather than a dedicated drill-results announcement. The absence of a headline announcement is itself information. If the same company would have headlined a strong intercept, the lack of a headline often means the results were below expectations.

The contrast pattern looks like this. Two companies drill maiden holes in the same week:

A is making the most of strong results. B is downplaying weak ones. The body of the announcements (or the absence of an announcement) tells you which is which.

The "body matches headline" check

A good announcement is one where the body confirms and elaborates on what the headline claims. The headline says "exceptional intercept"; the body shows hole-by-hole assays that include exceptional intercepts. The headline says "step-out drilling extends mineralisation 200m"; the body shows a plan view with the new holes plotted 200m beyond the prior boundary.

A bad announcement is one where the body softens the headline:

If you can't reconcile the headline to specific data points in the body, the announcement is doing more work as marketing than as information.

Cross-reference against other companies' announcements on the same district

When a company in a known mineral district announces results, look at what the neighbours are saying. Often other companies on adjacent tenements publish results that contextualise — sometimes they show the structure pinches out, or grades fall off in a particular direction, or a metallurgical issue is more widespread than originally implied. The full picture rarely lives in one company's announcement.

What a good drill announcement looks like

Green flags when reading:

When you see all of that, you're looking at a serious result. When you see "up to" headlines, no diagrams, and one big intercept with everything else "pending", treat the announcement as marketing.

A practical reading checklist

For every drill result announcement, answer:

  1. What type of drilling produced this intercept — grade control, infill, step-out, or exploration?
  2. What's the headline intercept in g·m?
  3. What's the true width vs down-hole length?
  4. Is the headline a single hole or multiple holes?
  5. Where does the hole sit — inside the existing resource boundary or outside?
  6. What's the high-grade core stripped out, vs the parent interval?
  7. Are there any single-metre assays driving the average?
  8. How many holes from the program are still pending? Why?
  9. Does the body of the announcement substantively support the headline, or does it walk it back?
  10. Does the geology match the deposit model the company is selling?

You will be ahead of 95% of retail if you do this for every announcement on every stock you hold.

Pre-event positioning patterns

The drill result trade is well-known and well-played:

Don't confuse "good drill result" with "good trade". The trade depends on what was already priced in.

What I'm uncertain about

Revision #2
Created 22 April 2026 02:16:56 by Conor
Updated 25 April 2026 02:29:43 by Conor