Gold

How to Read Drill Results

Information only, not investment advice. This guide explains how mining companies report results and raise money; it does not recommend any company or security.

By REE Stocks. Sources checked Oct 13, 2026.

A track-mounted drill rig and crew in high-visibility vests on a gravel mountain road, with snow-streaked peaks in the distance. — Photo: Mary Lewandowski, National Park Service (public domain)

A drill result is a line in a mining company's news release that reports how much metal was found over a length of drill core, such as "12 metres grading 3.2 grams per tonne gold". It shows that metal is there. On its own it can't tell you whether there's a mine, and the details around the headline number matter more than the number itself.

Junior miners publish drill results all the time, and share prices can move hard on a single hole. Once you know what the numbers mean and what a release must include, it's much easier to tell a solid result from a dressed-up one.

What does a drill intercept mean?

A drill intercept is a stretch of drill core with a measured grade, given as a length and a grade. "12 metres grading 3.2 g/t gold" means a 12-metre run of core averaged 3.2 grams of gold per tonne of rock. Precious metals are usually reported in grams per tonne. Copper, nickel and zinc are usually reported as a percentage.

Many results add an "including" line, such as "including 2 metres of 15 g/t gold". That is a shorter, richer stretch inside the longer interval. National Instrument 43-101, the Canadian disclosure rule for mining, requires companies to report any significantly higher-grade intervals within a lower-grade intersection. The "including" stretch is already part of the longer interval, so the two shouldn't be added together.

Why does true width matter?

True width is the actual thickness of the mineralized zone, and it often differs from the length of core reported. A hole that cuts across a vein at a sharp angle passes through more rock than the vein is thick. So 20 metres of core might come from a zone only a few metres wide. Our mining grade converter works out true width from the core length and angle.

NI 43-101 requires written disclosure of drill results to give the widths and, to the extent known, the true widths of the mineralized zone. Many companies still leave them out. Canadian regulators checked mining company investor presentations in a 2015 review. Of those reporting drill results, 38% gave no true widths. The regulators warned that results without them may be misleading.

What is the difference between diamond and RC drilling?

Diamond drilling cuts a solid cylinder of rock, called core, that geologists can log and split for assay. Reverse circulation (RC) drilling smashes the rock and brings up chips, which is faster and cheaper but shows less of the geology. A technical report should say which type was used.

The difference shows up in the sampling. RC holes are usually sampled at a constant length, the CIM exploration guidelines note. Core can be sampled in pieces that follow the geology, such as the edges of a vein.

How do you know the assays are reliable?

Assays are reliable when the company runs a quality control program and uses an independent, accredited laboratory. The CIM guidelines say samples should go to a reputable and preferably ISO-accredited lab. They also say a program should include blanks, certified reference materials (samples with a known grade) and duplicate samples, plus regular check assays at a second lab.

NI 43-101 requires a release to name each laboratory, its location and any relationship to the company, and to summarize the quality control used. The 2015 regulators' review found 67% of presentations left out that summary and 71% didn't name the lab and its location. If a release doesn't say who ran the assays, that's worth noticing.

What can a single drill hole tell you?

A single drill hole tells you metal is present at one spot, and very little more. BC Securities Commission staff put it plainly in a 2024 presentation: a single intercept says nothing about continuity, the volume of mineralization, mining methods, recoveries, costs or the prospects for economic extraction.

That's why NI 43-101 bars companies from stating the quantity or grade of a deposit until it has been put into a resource category. Turning holes into tonnes takes many more holes and a formal estimate, covered in How to Read a Rare Earth Resource Estimate. The rule behind that estimate is explained in What Is an NI 43-101 Technical Report?

What are metal-equivalent grades?

A metal-equivalent grade converts several metals into one, such as gold equivalent for a deposit with gold, silver and copper. It's a handy shorthand, but the result depends on the prices and recoveries chosen. Under the current rule, a company can't report an equivalent grade without also giving the grade of each metal.

The regulators want to go further. Their proposed 2025 replacement for NI 43-101 would also require the prices, recoveries and any other conversion factors used. It hadn't taken effect as of October 2026, but it's good practice to look for those numbers now.

What warning signs should you look for?

Warning signs are the shortcuts that make a result look better than it is. The BC Securities Commission staff presentation lists several to avoid:

Selective "up to" results that quote only the best sample.
Missing true widths.
Visual estimates of grade before assays come back.
Grade-times-thickness figures such as gram-metres, which the staff say present an unclassified accumulation of metal.
Gross metal values, such as the dollar value of metal in a hole.

The same presentation's advice to companies is to disclose all the results, good and bad. A release that shows every hole, including the weak ones, is usually easier to trust.

What should a drill-result release include?

A complete drill-result release gives enough detail to check the headline. Under NI 43-101, written disclosure of drill results should cover:

The location, azimuth and dip of each hole, and the depth of each sample interval.
The widths and, where known, the true widths of the zone.
Any significantly higher-grade intervals inside a lower-grade one.
Any drilling, sampling or recovery problems that could affect the results.
The analytical method, the lab's name and location, and a summary of quality control.

You can find listed companies by metal on our gold, copper and rare earth stock lists.

How to Read Drill Results: frequently asked questions

What does g/t mean in a drill result?

G/t means grams per tonne: the grams of metal in each tonne of rock. A result of 3 g/t gold means about 3 grams of gold in every tonne. Gold and silver are usually reported in g/t, while copper, nickel and zinc are usually reported as a percentage.

What is true width in drilling?

True width is the actual thickness of a mineralized zone, measured straight across it. A drill hole that crosses a zone at an angle passes through more rock than the zone is thick, so the core length is longer than the true width. Canadian rules require companies to report true widths to the extent they are known.

What does "including" mean in a drill result?

An "including" line reports a shorter, higher-grade stretch inside a longer, lower-grade interval. NI 43-101 requires companies to report significantly higher-grade intervals within a lower-grade intersection. The shorter interval is already counted inside the longer one, so the two should not be added together.

Is one high-grade drill hole a sign of a mine?

Not on its own. BC Securities Commission staff point out that a single intercept says nothing about continuity, the volume of mineralization, mining methods, recoveries or costs. It takes many holes, and then a resource estimate, before anyone can say how much metal a deposit holds.

What are gram-metres?

Gram-metres multiply grade by length, so 10 metres of 5 g/t becomes 50 gram-metres. BC Securities Commission staff caution that this kind of grade-times-thickness figure presents an unclassified accumulation of metal, which Canadian rules do not allow. Look at the grade and the width separately instead.