This article about how you can determine if a mining company's drill results are of low, medium or high grade is a great resource for investors in individual mining stocks. However, I recommend you to read this article too when you are investing in mining stocks through a Stock Based mineral ETF.
While 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 | |||||
| Mineralization | Symbol | Low Grade | Medium Grade | High Grade | |
| Base Metals | Cobalt | Co | less than 1% | 1% - 2% | over 2% |
| Copper | Cu | less than 0.5% | 0.5% - 1.5% | over 1.5% | |
| Iron Ore | Fe | less than 25% | 25% - 35% | over 35% | |
| Lead | Pb | less than 2.5% | 2.5% - 10% | over 10% | |
| Molybdenum¹ | Mo | less than 0.15% | 0.15% - 0.5% | over 0.5% | |
| Nickel | Ni | less than 1% | 1% - 2% | over 2% | |
| Zinc | Zn | less than 2.5% | 2.5% - 10% | over 10% | |
| Energy | Uranium² | U3O8 | less than 0.15% | 0.15% - 0.40% | over 0.40% |
| Fertilizers | Phosphate Rock | P2O5 | less than 25% | 25% - 30% | over 30% |
| Potash | K2O | less than 20% | 20% - 25% | over 25% | |
| Precious Metals | Gold | Au | less than 1.5 g/t | 1.5 g/t - 5 g/t | over 5 g/t |
| Palladium | Pd | less than 1.5 g/t | 1.5 g/t - 5 g/t | over 5 g/t | |
| Platinum | Pt | less than 1 g/t | 1 g/t - 2.5 g/t | over 2.5 g/t | |
| Silver | Ag | less than 10 g/t | 10 g/t - 50 g/t | over 50 g/t | |
Of course it is not only the grade that counts 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.
¹ Depending on the deposit, some companies do not report in pure molybdenum (Mo), but in molybdenum sulphide (MoS2). To determine MoS2 to be high, medium or low grade you should first convert it back to Mo by dividing it by 1.6681.
² Uranium grade is often reported in parts per million (ppm). To convert ppm back to a percentage (%) you have to divide it by 10,000.
