Educational note: This article is for informational purposes only and does not constitute financial or investment advice. Always conduct your own due diligence and consult a licensed financial adviser before making investment decisions.
A drill-result press release is the single most important document a junior mining company publishes. It is the first public disclosure of what lies beneath the ground — and the binary event that can move a share price 50% in either direction. But most press releases are written to emphasise the best results, and without the tools to read past the headline, you are evaluating a discovery at a significant disadvantage.
This guide walks through the anatomy of a drill-result announcement section by section, explains what every key number means, and gives you a practical checklist for separating the genuinely significant from the carefully worded.
If you have not yet read How to Read Assay Results, start there first — that article covers the underlying mechanics of grade, compositing, cut-off grade, true width, and QAQC that this article builds on.
What does a drill-result press release actually contain?
Most drill-result announcements follow the same structure, regardless of whether the company is listed on the TSX, ASX, or AIM. Understanding the layout helps you move efficiently to the information that matters.
| Section | What it contains |
|---|---|
| Headline | One to three “highlight” intercepts — the best holes from the program, stated as depth, grade, and interval |
| Corporate summary | Boilerplate description of the company, project, and location |
| Results narrative | Management commentary on what the results mean and how they fit the geological model |
| Results table | The full data: hole ID, collar location (easting/northing/RL), azimuth, dip, end-of-hole depth, and the mineralised intervals (from, to, length, grade) |
| JORC Table 1 / NI 43-101 disclosure table | The required technical disclosure: sampling method, sample preparation, analytical procedures, QAQC protocols, and any caveats on the reported widths |
| Qualified Person / Competent Person statement | The professional sign-off confirming that a registered and experienced geologist has reviewed the data |
| Forward-looking statement disclaimer | Legal boilerplate present in every ASX and TSX announcement |
The hierarchy matters. The headline and narrative are written to create excitement. The results table and disclosure table are where you do your actual analysis. Many retail investors never read past the narrative — which is exactly the gap that allows misleading results to circulate unchallenged.
How to read the headline intercept
A typical headline reads something like:
“HOLE ABC-042: 42.5 metres at 2.8 g/t Au from 75 m, including 6.0 metres at 11.4 g/t Au from 84 m”
Breaking this down:
- Hole ID (ABC-042): The unique drill-hole identifier. Cross-reference it in the results table to find the collar location, orientation (azimuth and dip), and end-of-hole depth.
- 42.5 metres: The interval length — the distance measured along the drill hole trajectory through the mineralised zone. This is the downhole (apparent) width, not the true thickness of the deposit, unless explicitly stated otherwise (see below).
- 2.8 g/t Au: The composite grade — the length-weighted average gold concentration across the 42.5-metre interval. One g/t = one gram of gold per tonne of rock = one part per million.
- from 75 m: The start depth of the mineralised interval — 75 metres below the drill collar (the point at which the drill entered the ground). This tells you how deep the deposit sits.
- including 6.0 metres at 11.4 g/t Au from 84 m: A sub-interval — a higher-grade section nested within the broader intercept. The presence of an “including” line is one of the most important things to look for.
What is the “including” line telling you?
The “including” sub-interval shows where the grade is actually concentrated. In the example above, the 6 metres at 11.4 g/t sits inside a 42.5-metre interval averaging 2.8 g/t. You can back-calculate what the remaining 36.5 metres outside the “including” zone averages:
Total value: 42.5 m × 2.8 g/t = 119 g·m
Sub-interval value: 6.0 m × 11.4 g/t = 68.4 g·m
Remaining value: 119 – 68.4 = 50.6 g·m over 36.5 m = ~1.4 g/t
So the broader 36.5 metres averages roughly 1.4 g/t — lower-grade material that wraps around the high-grade core. Whether that matters depends on the deposit type and the likely mining method. In an open-pit bulk-tonnage scenario, 1.4 g/t can still be economic. In a narrow-vein underground scenario, it may be dilution.
The pathological case — grade smearing — is when the “including” sub-interval carries almost all the value, and the headline interval is created by blending a narrow nugget of high-grade with wide zones of near-barren material. For example: “10 metres at 5.0 g/t, including 1 metre at 49.1 g/t” means the outer 9 metres averages approximately 0.1 g/t — effectively waste. The headline grade is mathematically correct but economically misleading.
The rule: always calculate what the material outside the “including” line grades. If that grade is below the likely cut-off for the deposit type, the headline width is cosmetic.
Downhole width versus true width: the most important number most press releases obscure
The interval reported in the headline is the downhole length: the distance measured along the drill hole from where mineralisation starts to where it ends. This is almost never the same as the true thickness of the mineralised zone — the actual perpendicular width of the deposit as it sits in the ground.
The distortion is purely geometric. If a drill hole intersects a steeply dipping vein at a shallow angle, it travels a long distance through the vein even though the vein itself is thin. The same vein, intercepted perpendicular to its contacts, would give a downhole length equal to the true thickness.
As a rough guide:
| Angle between drill and mineralisation (°) | Apparent downhole width vs. true width |
|---|---|
| 90° (perpendicular) | 1.0× — no distortion |
| 60° | ~1.2× |
| 45° | ~1.4× |
| 30° | ~2.0× |
| 20° | ~2.9× |
| 10° | ~5.8× |
A 40-metre downhole intercept in a hole that intersects a steeply dipping vein at 30° represents approximately 20 metres of true vein thickness. The same result in a hole perpendicular to the vein is 40 metres. These are very different discoveries at the same grade.
What to look for in the disclosure table
Under both JORC (2012) and NI 43-101, companies are required to state whether widths are downhole or true widths, and to provide the drill orientation data (azimuth and dip) and the estimated orientation of the mineralised zone (dip and strike), so that readers can calculate true width independently.
If a press release reports wide intervals without stating whether the widths are downhole or true, and without providing drill orientation data, that is a material omission. Either the company does not know, or it is declining to disclose. In both cases, the economic significance of the intercept cannot be assessed.
Gram-meters: the one-number quality test
Gram-meters (also written g·m or grade-thickness) is the product of the composite grade and the interval length:
Gram-meters = Grade (g/t) × Interval (m)
It is the most useful quick comparison tool for gold intercepts because it captures both thickness and grade in a single number, allowing you to rank holes across different projects on a common basis.
General benchmarks for gold intercepts:
| Gram-meters | Significance |
|---|---|
| < 10 g·m | Marginal — useful only if at surface with very low strip ratio |
| 10–50 g·m | Solid result warranting follow-up drilling |
| 50–150 g·m | Significant — defines meaningful zones in most deposit settings |
| > 150 g·m | Exceptional — the kind of intercept that builds mines |
Examples:
- 2 m at 20 g/t = 40 g·m (high-grade but narrow — underground vein territory)
- 100 m at 0.5 g/t = 50 g·m (lower grade but bulk-tonnage — open-pit territory)
Both score similarly on gram-meters, but the first is a narrow high-grade vein and the second is a bulk-tonnage target. Which is more valuable depends entirely on the project’s economics and the intended mining method.
For base metals — copper, zinc, nickel — the equivalent metric is percent-meters or kg/t·m. The principle is identical: grade multiplied by width gives a normalised quality measure you can compare across holes.
Cut-off grade: why the same drill hole can produce very different reported intercepts
A cut-off grade is the minimum grade at which material is included in a mineralised composite. Material below the cut-off is treated as waste for the purposes of defining the intercept. The choice of cut-off grade directly controls the width and grade of the reported interval.
A simple example: imagine five consecutive one-metre samples returning 0.2, 1.8, 3.1, 0.8, and 0.1 g/t Au. At a cut-off of 0.5 g/t, the composite is reported as “2 m at 2.45 g/t from 1 m” (samples 2 and 3 only). At a cut-off of 0.1 g/t, all five samples fall in, and the composite becomes “5 m at 1.2 g/t from 0 m”.
Neither composite is wrong — they reflect different economic assumptions. But a company that applies a 0.1 g/t cut-off to a deposit that will realistically require underground mining at a 3 g/t cut-off is reporting an interval that does not represent the mineable zone. Always check that the stated cut-off grade is consistent with the deposit type and mining method.
Typical cut-off grades as a rough reference:
| Deposit / Mining Method | Typical Cut-Off Grade |
|---|---|
| Open-pit gold (Carlin-type) | 0.15–0.35 g/t Au |
| Open-pit gold (heap leach oxide) | 0.25–0.45 g/t Au |
| Underground gold (narrow vein) | 3.5–5.0 g/t Au |
| Open-pit porphyry copper-gold | 0.15–0.25% CuEq |
| Underground base metals | 1.5–3.0% ZnEq or CuEq |
If a company does not state its cut-off grade, the intercept cannot be evaluated. This is a minimum disclosure requirement under both JORC and NI 43-101.
Depth and location: the economics of the intercept
Two intercepts with identical grade and width can have vastly different economic significance depending on how deep they sit.
Shallow (0–200 m vertical depth): Lower grades can be economic because open-pit mining is relatively cheap. An intercept at 100 m depth can be accessed with a modest strip ratio and processed in bulk at low per-tonne cost. The surface footprint of the mineralisation (area × thickness) matters as much as the grade.
Intermediate (200–500 m depth): May still be accessible by open pit, but the strip ratio rises and the economics tighten. Grade requirements increase.
Deep (>500 m depth): Almost certainly underground territory. Underground mining typically requires sustained grades of at least 3.0–5.0 g/t Au (or equivalent) to cover the significant capital cost of shaft sinking, ventilation, and underground development. A 100-metre-wide intercept grading 0.8 g/t at 800 m depth is unlikely to be economic under most scenarios.
The start depth (“from X m”) in the headline intercept is the first depth you should note. Then check whether the company has disclosed the vertical depth (which requires knowing the drill hole dip) — some companies report only downhole depth, which can be shallower than it appears if the hole is drilled at a steep angle.
Step-out versus infill drilling: what is the program trying to do?
Not all drill holes serve the same purpose. Understanding the intent of the program sets the right expectation for what a “good result” looks like.
Step-out holes move the drill rig away from known mineralisation — 50, 100, or 500 metres along strike or down-dip — to test whether the deposit continues. A successful step-out extends the known dimensions of the system and adds “blue sky” — the open-ended potential for further discoveries. These holes carry the highest exploration risk and, when they succeed, deliver the largest share-price response.
Infill holes target gaps between previously successful holes to prove continuity and upgrade the resource category from Inferred (low-confidence) to Indicated (bankable). An infill hole that hits was expected to hit. If it misses, it is a significant problem — it breaks the geological model and erases assumed tonnes and ounces.
Resource definition holes drill a tightly spaced pattern across a known zone to convert Indicated to Measured resources for pre-feasibility and feasibility studies.
The press release should identify which type of program is underway. If it does not, the hole ID numbering sequence sometimes provides a clue — a sudden jump in the sequence (e.g., from ABC-020 to ABC-031) may indicate that the company has not yet reported all holes.
The Qualified Person / Competent Person statement
Every JORC-compliant and NI 43-101-compliant press release must include a sign-off from a registered technical professional who takes personal responsibility for the scientific content. Under JORC, this is the Competent Person (CP) — typically a member in good standing of the AusIMM, AIG, or an equivalent body with at least five years of relevant experience in the deposit type. Under NI 43-101, the equivalent role is the Qualified Person (QP), a definition set by the Canadian Securities Administrators.
The CP/QP statement typically appears at the end of the announcement, names the individual, states their professional designation and membership body, and confirms that they have reviewed the release. The existence of a properly stated CP/QP does not guarantee that the results are meaningful — but its absence is a serious red flag. If no named, qualified individual has signed off on the technical content, the announcement does not meet the minimum disclosure standards of the relevant stock exchange.
The JORC Table 1 / NI 43-101 disclosure checklist
Appended to most serious JORC announcements is a Table 1 — a standardised checklist that the company is required to complete for any material announcement of new drill results. It covers:
- Sampling techniques and data: How core was sampled, what sample size was used, whether the core was oriented
- Drilling techniques: Drill type (diamond, RC), hole diameter, casing, water pressure
- Sample preparation: Crushing, drying, splitting, pulverising protocols
- Quality of assay data and laboratory tests: Which laboratory was used, what analytical method (fire assay, ICP, XRF), QAQC procedures (standards, blanks, duplicates and their results)
- Verification of sampling and assaying: Whether twin holes were drilled, whether results were validated by an independent party
- Location of data points: Datum, coordinate system, whether a differential GPS was used for collar surveys
- Data spacing and distribution: Drill spacing relative to resource estimate categories
- Orientation of data in relation to geological structure: How the drill holes are oriented relative to the mineralised zones and whether true widths have been calculated
The depth of disclosure in Table 1 is itself an indicator of quality. A Table 1 that answers every criterion with substantive detail — naming the laboratory, stating the CRM insertion rate and acceptance criteria, describing the compositing protocol — is the output of a program run to professional standards. A Table 1 that answers most items with “not yet determined” or “will be disclosed in future reports” is a caution sign.
A practical reading checklist
When you open a drill-result press release, work through this sequence before forming a view:
- Find the results table, not just the headline. Check whether the reported holes are a selective highlight or the complete results of the program. Look for gaps in the hole numbering sequence.
- Are the widths downhole or true? If true widths are not stated, find the drill orientation data (azimuth and dip) and the structural data (zone dip and strike) and estimate the correction yourself.
- Calculate gram-meters for each highlighted intercept. Where does it sit relative to the benchmarks for this deposit type?
- Check the cut-off grade. Is it stated? Is it consistent with the expected economics of the project?
- Evaluate the “including” line. What does the material outside the sub-interval grade? Is the headline width real or cosmetic?
- Note the start depth. Is this intercept at open-pittable depths or is it deep underground?
- Is this step-out or infill drilling? Set your expectations accordingly.
- Read the QAQC disclosure. Did the standards pass? Are the failure criteria stated? A result with no QAQC disclosure is untested data.
- Find the CP/QP statement. Who signed off? Are they named and qualified for this deposit type?
- Check for metal equivalents. If the headline grade is AuEq or CuEq, find the footnote. What metal prices, recoveries, and co-products were used? Recalculate with conservative assumptions.
FAQ
Why do companies sometimes report only selected holes rather than all holes drilled?
JORC (2012) requires that all “material” results be reported promptly once the company is aware of them, and that companies not cherry-pick only positive results while suppressing negative ones. In practice, companies have some latitude in defining “material”. Gaps in the hole numbering sequence — e.g., holes ABC-018 through ABC-023 reported, then ABC-027 through ABC-030 — may indicate that unreported holes are pending laboratory results, or that the company is delaying reporting of poor results. A request to the company for the status of all holes in the program is entirely legitimate.
What is the difference between vertical depth and downhole depth?
Downhole depth is measured along the drill hole trajectory from the collar. Vertical depth is the straight-line distance from the collar to the mineralised zone measured vertically downward. Because drill holes are angled (typically drilled at -55° to -70° from horizontal), the vertical depth is always less than the downhole depth. For a hole drilled at -60°, the vertical depth to an intercept at 200 m downhole is approximately 173 m. When a company states only downhole depth, a shallow-dipping hole at significant downhole distance may still be quite accessible from surface.
Can I calculate true width from a press release?
If the company discloses the drill hole dip, azimuth, and an estimate of the dip and strike of the mineralised zone, you can calculate an approximate true width geometrically. Many exploration databases and online calculators can perform this calculation. The simplified formula for a planar zone and a straight hole is: true width = downhole interval × |sin(α)|, where α is the angle between the drill hole orientation and the plane of the mineralised zone. If the company has not disclosed both the hole orientation and the zone orientation, the calculation cannot be performed — and that absence is informative.
What is grade smearing, and how do I detect it?
Grade smearing describes the practice of calculating a composite grade across a wide interval that contains a short high-grade sample and wide flanking waste. The composite grade is mathematically correct but does not represent a mineable zone. To detect it, find the individual sample data (usually in Table 1 or a supplementary data file), identify the high-grade samples, and calculate what the remaining interval grades without them. If the “including” sub-interval carries more than about 70–80% of the total metal value of the headline intercept, look closely at the continuity and mining geometry.
What does “open at depth” mean?
When a company states that a mineralised zone is “open at depth” or “open along strike”, it means the drill program has not yet closed off the zone — there are no holes yet below the deepest intercept, or no holes to the north or south of the furthest intersections. Open-ness is a positive statement about discovery potential but not evidence of what is actually there. It is one of several caveats that can legitimately accompany early-stage results.
How Blue Butterfly helps geologists produce the data that investors rely on
The numbers in a drill-result press release originate in a geologist’s core-logging record. The grade in the headline composite is a length-weighted average of individual assay samples that were collected, labelled, dispatched to the laboratory, and validated against QAQC benchmarks before they were ever composited into an intercept. Each step in that chain depends on accurate, consistent, and auditable data management.
Blue Butterfly captures the geological log, the sampling record, and the laboratory dispatch in a single browser-based database — offline-capable at the drill site, synced to the cloud when connectivity returns. When the assay certificate arrives, results are imported, matched to the sampling record by hole ID and depth interval, and flagged automatically against expected QAQC values. The geologist sees failures immediately, before they propagate into a resource estimate or a press release.
For investors, the downstream effect is a data trail that is complete, traceable, and correctly formatted for the disclosure tables that underpin credible announcements.
See how Blue Butterfly manages drill data from log to assay →
Sources
- Small Cap Investor — How to Read and Interpret Drill Results (gram-meters benchmarks; true width vs. apparent width; grade smearing examples; step-out vs. infill drilling): https://smallcapinvestor.ca/the-truth-machine-how-to-read-and-interpret-drill-results/
- Discovery Alert — Decoding Drill Results: A Guide to Mineral Exploration Analysis (press release anatomy; selective reporting practices; cut-off grade ranges by deposit type; QA/QC protocols): https://discoveryalert.com.au/mineral-exploration-drill-results-interpretation-2025/
- Mining.com — A Primer on Reading Drill Result Press Releases (Brent Cook on grade smearing as the top disclosure flaw; importance of complete data including drill maps and sections): https://www.mining.com/web/a-primer-on-reading-drill-result-press-releases/
- Resource World Magazine — Making the Grade: Understanding Exploration Results (grade-thickness calculation; unit explanations; depth significance; open pit vs. underground context): https://resourceworld.com/making-grade-understanding-exploration-results/
- Next Investors — How to Read Assays and Drilling Results for Beginners (headline components; cut-off grade; grade-thickness metric): https://nextinvestors.com/learn-to-invest/mining/how-to-read-assays-and-drilling-results-for-beginners/
- Mining.com.au — How Drill Results Are Reported and Interpreted (results table components; JORC disclosure requirements; intercept reporting conventions): https://mining.com.au/how-drill-results-are-reported-and-interpreted/
- Crux Investor — Analyst’s Notes: How to Read Drill Results & Numbers to Watch Out For (press release structure; red flags in drill announcements; weighted average verification): https://www.cruxinvestor.com/posts/analysts-notes-week-4
- Gilbert Analytics — How to Read Drill Results: What the Numbers Actually Mean (gram-meters framework; depth significance for open-pit vs. underground; true width geometry): https://gilbertanalytics.substack.com/p/how-to-read-drill-results-a-practical
- National Instrument 43-101 (CSA) — Standards of Disclosure for Mineral Projects (requirements for hole orientation disclosure, true width, QP statement, QAQC data): https://mrmr.cim.org/media/1017/national-instrument-43-101.pdf
- Discovery Alert — JORC Code: Essential Guide to Mining Compliance Standards (JORC Table 1 checklist items; Competent Person requirements; material disclosure obligations): https://discoveryalert.com.au/jorc-code-mining-compliance-2025/
- Latin Mines — Drill Result Analysis Part 1 (systematic approach to filtering drill results; grade-thickness calculations; hole context analysis): https://latinmines.com/drill-result-filtering/