A Beginner’s Guide to Reading Drill Results

For most retail investors, reading a mining press release can feel like deciphering hieroglyphics. Drill intercepts, grades, true widths — it’s a world of jargon and numbers that can either signal a major discovery or a complete dud. Yet behind every dense table or flashy headline lies the potential for the next great discovery.

Learning how to interpret drill results is one of the most valuable skills in resource investing. It’s how early investors spotted companies like Snowline Gold in 2022 or Great Bear in 2018 long before the market caught on.

Let’s break it down.

1. The Basics: Grade, Width, and Depth

A drill intercept tells you three things:

• How much mineralization was hit (width)

• How rich it is (grade)

• At what depth it was encountered

For gold, grades are expressed in grams per tonne (g/t).
For copper, grades are shown as a percentage (% Cu).

Rule of thumb:

Gold

• Below 0.5 g/t = low grade

• 1–3 g/t = moderate

• 5+ g/t = high grade

• 10+ g/t = exceptional (often narrow vein, underground)

Copper

• Below 0.3% = low grade

• 0.5–1.0% = solid

• 1.5%+ = high grade

However, grade alone doesn’t determine value. Width and geometry often matter more. A one-metre intercept at 30 g/t might look incredible, but a 200-metre intercept at 1 g/t can be far more significant in an open-pit scenario.

Example (Gold):
“200 m @ 1.1 g/t Au from surface” — a strong indicator of a large, bulk-tonnage system.

Example (Copper):
“100 m @ 0.8% CuEq from 50 m depth” — impressive near-surface porphyry mineralization.

2. True Width vs. Core Length

Most results are reported as core length, which measures the mineralized interval along the hole. But because ore bodies are rarely perfectly horizontal, the true width (the actual thickness of the mineralized zone) is often smaller.

Good companies clearly state whether results represent true width or core length. If that information is missing, take caution. Without geometry, results can appear stronger than they are.

3. Context Is Everything

A result that looks mediocre on paper can be exceptional in the right geological setting.

• In gold, 1 g/t can be fantastic if it’s near surface and continuous, as seen in open-pit systems across Nevada, the Yukon, and Australia.

• In copper, 0.5% Cu can be world-class if it extends for hundreds of metres in a porphyry system.

Always compare results to similar deposits in the same district. For instance, if Snowline Gold hits 318 m @ 2.5 g/t Au at its Valley discovery, and a nearby explorer reports 220 m @ 1.1 g/t Au in the same intrusive corridor, that second result is still very meaningful. It suggests the same mineralizing system could extend across claims.

4. Grade × Thickness = Metal Factor

To quickly gauge the strength of an intercept, multiply grade × width — known as the metal factor.

For gold:

• 10 m @ 10 g/t = 100 (short but rich)

• 200 m @ 0.5 g/t = 100 (lower grade, but bulk tonnage style)

For copper:

• 100 m @ 1% Cu = 100 (excellent)

• 300 m @ 0.3% Cu = 90 (lower grade, but impressive continuity)

It’s not a perfect metric, but it helps investors compare different results on an apples-to-apples basis.

5. Infill Drilling vs. Step-Out Drilling

Once a discovery is made, companies usually shift between two types of drilling: infill and step-out. Understanding the difference is crucial.

• Step-out drilling is about growth. It tests new ground outside the known mineralized area to see how far the system extends. Step-outs that hit mineralization can dramatically expand the potential size of a deposit and generate excitement in the market.

• Infill drilling is about confidence. It targets gaps within the known deposit to increase resource certainty, often upgrading “Inferred” ounces to “Indicated” or “Measured” in preparation for an economic study.

A successful discovery phase often alternates between the two: step-outs to grow the footprint, and infill holes to tighten the model and move closer to defining a mineable resource.

When you read a news release, note whether the company is drilling to expand or to define. Step-out success tends to move share prices the most, while infill work adds long-term value by improving the resource quality.

6. The Surrounding Holes Matter

One great hole doesn’t make a deposit. Consistency across multiple holes does.

Watch for how results evolve over time. Are grades and widths holding up as the company drills further away from the discovery hole? Are they finding continuity along strike and at depth?

The best discoveries grow logically — 50-metre step-outs that confirm mineralization continues, deeper holes that extend the system vertically, and cross-sections that start to fill in like puzzle pieces.

7. Watch the Headlines and the Fine Print

Exploration companies love flashy headlines. “Bonanza-grade” intercepts can look spectacular but often represent very short intervals that have little impact on overall economics.

Example: “0.5 m @ 120 g/t Au” sounds incredible, but it could just be a narrow vein surrounded by waste rock.

The most valuable information usually hides in the longer intercepts or the geological commentary further down the release. Always read the full table of results and pay attention to the notes on geometry and mineralization style.

8. Copper and Gold Equivalents

In polymetallic systems, companies often use AuEq (gold equivalent) or CuEq (copper equivalent) to simplify reporting. This combines multiple metals into a single figure based on relative market prices and assumed recoveries.

It’s a useful comparison tool, but remember that equivalencies are only as accurate as the assumptions behind them. Metal prices fluctuate, and recovery rates can vary by deposit.

9. Case Studies: When the Numbers Come Alive

Gold Example – Snowline Gold
Snowline’s Valley discovery in the Yukon is a textbook example of a bulk-tonnage gold system. Intercepts such as 318.8 m @ 2.55 g/t Au captured the market’s attention not because of ultra-high grades, but because of the exceptional combination of width, continuity, and proximity to surface. The geometry made it an ideal open-pit candidate, which is why the company’s valuation exploded.

Copper Example – Solaris Resources
At the Warintza Project in Ecuador, Solaris reported 660 m @ 0.97% CuEq — nearly half a kilometre of strong, continuous mineralization from surface. That single hole demonstrated the open-pit potential of the system and was enough to re-rate the company from a penny stock to a multi-billion-dollar developer within months.

These examples show what happens when grade, width, and location align.

10. The Bottom Line

When you see a drill headline, focus less on the adjectives and more on the context. Ask yourself:

• Is the mineralization wide, continuous, and near surface?

• Are results reported as true width or core length?

• Is the company expanding the system or tightening its resource model?

• How do the results compare to nearby or analogous deposits?

Interpreting drill results isn’t about chasing the highest number. It’s about understanding what those numbers mean geologically and economically.

Once you can read a drill release with that lens, you stop reacting to hype and start identifying genuine discoveries while they’re still under the radar. That’s where the biggest gains are made.