komatite for dummies...

The market really hasn't grasped the significance of this announcement. And considering the understated way it was written I can understand why. The significant part is not the grades it's the fact that 28 of 35 holes found komatite ultramafics. The fact that 2 of them found disseminated sulfides is the icing on the cake and last piece of the puzzle that proves a critical point.

This was never going to a Nova discovery announcement. It's a first recon drill program. I very much doubt they thought they'd hit massive sulfides this time around. It's spread across a huge area to define the region of prospectivity. 30km is massive. To put it into context the primary Kambalda zone (one of BHP's big 3 nickel mines) is about 5km * 5km.

Understanding why it matters requires an understanding of the relationship between komatite and Ni sulfide deposits. I'm not a geo but I do a lot of studying and believe I understand this so I thought I'd put together an explanation of how komatites and sulfides are formed.

First a few definitions...

Ultramafic

A type of igneous rock very low in silica content. Formed by molten magma creeping up through faults in the earths crust and cooling. It's important to remember that during the formation process it is liquid so the different elements that make up the magma are free to move around.

Komatite

Kind of a subset of ultramafic rock. I say 'kind of' because true komatites are all ultramafic but there are other types of rock similar that aren't true komatites. This matters because these rocks have been specifically identified as ultramafic komatites.

Sulphides

Any element bonded with sulfur. Ni and other base metals we are interested in have a preference for bonding with sulfur over other potential partner elements contained within the magma juice.

Formation Process

A typical intrusive ultramafic formation setting is for the liquid magma to force it's way from the molten core of the planet through faults in the crust towards the surface. It pushes the host rocks apart to form a space. As it flows it will partially melt some of the walls of the host rock. Then when it's reached a pressure equilibrium it starts the long cooling process to become solid rock.

In it's initial liquid form all the different elements are reasonably evenly dispersed, kind of like a well mixed drink. Once the cooling process begins though that starts to change. The sulfur we are looking for comes from two sources. One is the komatitic magma itself, the other is from the host rock walls that are partially melted during the intrusion. While it's flowing these can get nicely mixed up and any extra sulfur can bond with the base metals in the magma. Greenstone is one such sulfur bearing host rock which just happens to be all over SGQ's block.

The fun bit happens once the flow has stabilised, think if it like mixing dirt into water with a spoon then stopping and let the water become still. The sulphides are denser than the other components of the fluid so they start to sink to the bottom and settle there. What was once a very highly dispersed bunch of nickel becomes highly concentrated at the bottom of the magma chamber.

Now you might assume that means there should be a layer of sulfides under the komatites and all you have to do is drill right through the komatite to know if there's Ni there. If the bottom surface of the host rock was flat that might be true. But it's not, it's got lots of peaks and valleys in it. The sinking sulfides will accumulate in the valleys leaving distinct barren and mineralized zones. Since these valleys tend to be elongated that's why EM conductors are often long and skinny rather than square shaped blobs.

Disseminated Sulfides

We all want massive sulfides not these pizzling disseminated ones. But they are a good thing. The process I've described above takes an awfully long time. If the magma cools too quickly then some portion of the sulfides won't have had time to migrate to the bottom. Why it's a good thing is that it's a marker. The fact they are there tells us one critical thing. There was sulfur there to begin with which means the massive sulfides are down there somewhere waiting to be found.

Conclusion

I haven't covered some of the post formation events that can occur like metamorphism and remobilization. That's a story for another post. But in any case they wouldn't alter the fact that what's been found on this first pass is flashing neon sign that says 'come find your nickel'. I'm sure the market will take some more convincing. But for now I'm happy for the price to dither around so I can accumulate. If I said what I really think of the potential here I'd be hounded for ramping so I'll just keep that to myself.