Gold Drill Results: Intercept Length, True Width, and Grade

Gold exploration headlines often highlight an interval such as “20 metres at 3 grams per tonne.” That number can be useful, but it is not a complete investment conclusion. A careful review also asks how the hole crossed the mineralized structure, whether the reported length approximates true thickness, how samples were collected and whether nearby drilling supports continuity.

Evergreen investor education. This article does not describe results from a GBDS project.

Start with what the interval measures

A drill intercept normally describes the length measured along the drill hole. True width is the estimated thickness of the mineralized body measured perpendicular to its boundaries. If an angled hole cuts a steeply dipping vein at a shallow crossing angle, the downhole intercept can be materially longer than the true width.

Investors should look for the hole’s azimuth and dip, the interpreted orientation of mineralization, and a statement explaining whether true width is known. Where geometry remains uncertain, the uncertainty matters. The JORC Code establishes minimum standards for public reporting of Exploration Results, Mineral Resources and Ore Reserves and uses a transparency-and-materiality framework intended to inform investors.

Grade multiplied by length is only a screen

Analysts sometimes multiply grade by interval length to compare headline results quickly. This “gram-metre” figure can help organize a large table, but it does not estimate contained ounces or economic value.

Hypothetical example: 20 metres at 3 g/t equals 60 gram-metres, while 5 metres at 12 g/t also equals 60 gram-metres. The results are not interchangeable. They may imply different mining methods, dilution exposure, continuity, processing behavior and development requirements. The comparison is even less meaningful if one interval is close to true width and the other is not.

Read the sampling details

Check the individual sample lengths used to build the reported composite. Ask whether lower-grade internal intervals were included, whether high grades were capped, and whether the company reports both broad mineralized envelopes and narrower high-grade zones. Selective presentation can make a result appear more consistent than the underlying assays.

Quality-assurance information should describe core recovery, sample preparation, laboratory methods and the use of certified standards, blanks and duplicates. These controls do not guarantee a discovery, but they help readers judge whether the assay data are reliable enough for the stated purpose.

One strong hole is not a mineral resource

A mineral resource interpretation depends on geology, multiple drill holes, spacing, continuity, data quality and reasonable prospects for eventual economic extraction. The CIM Definition Standards distinguish Exploration Results from Mineral Resources and Mineral Reserves and define increasing levels of geological confidence. A notable intercept may justify follow-up drilling without supporting a resource estimate.

Investor checklist for drill-result releases

• Is the interval downhole length or estimated true width?
• Are hole location, azimuth, dip and mineralized geometry disclosed?
• Are complete assay tables, maps and cross-sections available?
• Do nearby holes support grade and geological continuity?
• Are sampling, laboratory and quality-control procedures explained?
• Could high-grade outliers dominate the reported average?

The takeaway

Strong gold drill results can be an important technical milestone, but the headline grade and length are the beginning of due diligence. Geometry, true width, data quality, continuity and the stage of evaluation determine how much weight an investor should place on any single interval.

Educational information only; not investment, legal or technical advice. Mining and exploration investments involve substantial risk, including geological uncertainty, commodity-price volatility, permitting, financing and execution risk. Review qualified technical disclosure and seek appropriate professional advice before making investment decisions.