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True width and gram-metres

Convert a drill hole's core length into the true width of the zone, and compare intercepts in gram-metres.

Example numbers are loaded. Replace them with figures from the company's own filings.
True width
10.39 m
87% of the core length
As reported
12 m of 3.1 g/t
Gram-metres on core length (g/t × m)
37.2
Gram-metres on true width (g/t × m)
32.22

How it works

Drill results are reported as a length of core, such as 12.0 m of 3.1 g/t. If the hole crosses the zone at an angle, the zone is thinner than the core length.

True width is the core length times the sine of the angle between the hole and the zone. At 90 degrees the two match. At 30 degrees the zone is half as wide as the core length. A release should say whether widths are true widths or core lengths, and estimate the true width when it is known.

Gram-metres (grade times length) put a short high-grade hit and a long low-grade one on the same scale. The calculator shows them on both the core length and the true width.

Read the guide: How to Read a Junior Mining News Release →

For education only. Not investment advice. The results are only as good as the numbers entered; check every figure against the company's own filings. See the Disclaimer.

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