Hello Bullish,

As far as your question on geophysics sometimes they can be very helpful in diamond exploration and sometimes they aren't. One problem is how magnetic the country rock is in the area. If there is a lot of magnetic noise in the country rock it can make interpretation very difficult. Another issue is that kimberlites can range from highly magnetic to only slightly magnetic. So if the country rock is noisy and the kimberlite is slightly magnetic it is practically invisible.

On the other hand when diamond indicator minerals are found in the surface samples you learn very important information. The first thing to remember is that diamond indicator minerals grow in the upper mantle and they make their way to the surface via a kimberlite intrusion. So those diamond indicator minerals have to have a source kimberlite. Additional information can be gleaned from the individual indicator mineral grains. Kelyphitic rims are a very thin outer coating on the outside of the garnet and if that is still intact it is a strong indication that the source kimberlite is close because that coating doesn't survive for very long when moved by a glacier.

Thus is you find an area with high counts of indicator minerals and they have kelyphitic rims on the garnets you are usually close to the source kimberlite. Then the next important step is to study the topography and look for lakes or lowlands near those indicator mineral anomalies and those are the kinds of targets to start drilling. Of course if you also have geophysical targets in the area those would also be worth drilling, basically in exploration you want to try and turn over every rock.

Cheers,

Allan