Drilling Results – How Can You Determine if a Mining Company’s Drill Results are of Low, Medium or High Grade

Whilst drilling results of base metals are reported in a percentage per tonne (%), drilling results of precious metals are reported in grams per tonne (g/t).

For an investor it is very important to know if a drill result is low-, medium- or high grade: this gives you the first impression of the possible financial outcomes of the deposit.

After analyzing and interpreting various drill reports to distinguish low grade, medium grade and high grade mineralization from each other, I have summarized my findings in the following table:

Low Grade, Medium Grade and High Grade Mineralization

ⓘ If on a mobile device, swipe the table to see all data points.
 MineralizationSymbolLow GradeMedium GradeHigh Grade
Base MetalsCobaltColess than 1%1% – 2%over 2%
CopperCuless than 0.5%0.5% – 1.5%over 1.5%
Iron OreFeless than 25%25% – 35%over 35%
LeadPbless than 2.5%2.5% – 10%over 10%
Molybdenum1Moless than 0.15%0.15% – 0.5%over 0.5%
NickelNiless than 1%1% – 2%over 2%
ZincZnless than 2.5%2.5% – 10%over 10%
EnergyUranium2U3O8less than 0.15%0.15% – 0.40%over 0.40%
FertilizersPhosphate RockP2O5less than 25%25% – 30%over 30%
PotashK2Oless than 20%20% – 25%over 25%
Precious MetalsGoldAuless than 1.5 g/t1.5 g/t – 5 g/tover 5 g/t
PalladiumPdless than 1.5 g/t1.5 g/t – 5 g/tover 5 g/t
PlatinumPtless than 1 g/t1 g/t – 2.5 g/tover 2.5 g/t
SilverAgless than 10 g/t10 g/t – 50 g/tover 50 g/t

Of course it is not only the grade that count since there are a lot of profitable mining operations around the world which are developing low- to medium grade ore. Therefore it is better to use gram-meters instead of only looking at the grade when comparing the drill results of different companies. An example:

  • Company ABC reports drill results: 1 meter, containing 250 g/t Gold = 250 gram-meters
  • Company XYZ reports drill results: 50 meters, containing 5 g/t Gold = 250 gram-meters

As you can see both companies report the same amount of gram-meters. In order to determine which project would be the better investment, you need to know about the mining costs, the break even analysis and the metal value, after which you can compare both projects with each other and draw your own conclusions. To learn more about the mining costs, the break even analysis and the metal value, I recommend you to read these pages too, which you can by clicking the links provided.


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