Mantle Nodules

Mantle nodules sometimes called mantle xenolith's are basically rocks that were formed in the mantle layer and made it to or near surface via kimberlite.

*Information in this current blog is based on information obtained up to mid 2018 and should be considered legacy at this time and should no longer be relied upon.*



Why is this important?  Some of these nodules that were created within the mantle layer contain diamonds that were also created at the mantle layer. The diamonds within the nodule are well protected on ascent to the surface. During the journey to surface, many of these nodules will disaggregate and these diamonds will be dispersed over a much wider area. These are the diamonds you see in a kimberlite pipe. Where this does not happen, those nodules could have a significant amount of diamond content (up to 10 carats in 1 pound of material).

These nodules have very similar densities to diamonds (3.5 grams per cubic centimetre).
This makes processing a bit tricky. The dense media separation (DMS) unit uses the difference between the diamond density and the host rock density to separate the two. This is a good and bad thing for nodules...the bad thing is you could end up with a lot of nodule material post DMS that you have to deal with (these may or may not contain diamonds)...the good thing is that if they do contain diamonds, you haven't thrown them away with the host rock material.

Chidliak is in the process of bulk sampling CH-7 that is known to contain mantle nodules.
The density sample chart for CH-7 clearly shows some denser material and overall, CH-7 is denser than CH-6.


Do we know if Chidliak nodules do contain diamonds?
From the 2015 Technical report on CH-6, we get this little snippet from the microdiamond section:

"Three sample aliquots totalling 23.66 kg (two from KIM-L weighing 15.6 kg, and one
from KIM-C weighing 8.06 kg) that contain over 10 times more microdiamonds than is
typical for CH-6 kimberlite. These results are interpreted as “nugget” effects related to
the presence of diamond-bearing mantle xenoliths"

So, they purposely excluded the results because it would overwhelm such a small sample. This confirms presence of high content diamond nodules at Chidliak.

Here are many images of mantle nodules from Chidliak:

CH-1:

CH2:

 CH6:







CH7:



 CH31:


CH51:


CH58:






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