@stockbluesky ... Not a bad idea for a thread, so we can compare different Niobium finds and work out why there are vastly different Mcaps for the different companies...
Firstly, an understanding of where we find high grade Niobium is in order. It's the preserved weathered section of the intrusion. The carbonatite intrusion, which is relatively uncommon by itself, has to weather down over time. As it weathers the heavier minerals like the Niobium and REE tend to stay in place in an oxidised form, while the lighter surrounding minerals can be eroded away.
Think of 200m thick of intrusion that has weathered for millions of years, the oxidised layer becomes more enriched than the original intrusion as we now have most of the minerals spread over only 20-50 metres instead of the original 200m in thickness.
Of course another important aspect is preservation. At Luni the age is looking to be around 1.7-1.8B years old
@salpetie will find the exact age eventually..
Once the intrusion has come to near surface then be weathered, is has to remain in place for all that time and not be 'moved' by forces of volcanic action, erosion, even meteor hit over that length of time. Throughout the world there are quite a few large carbonatite intrusions, without much of the weathered layer remaining, so they tend to be the 0.3-0.6% deposits.
Even here at Luni, it might not be of much importance what lies deep below the surface, as it's likely to be the 0.3-0.6 type of carbonatite. There are several of these 'planned' to be mined around the world like 'Globe' in Africa with a grade of 0.3% Nb2O5. The problem for most is the low grade and high expense of the capital requirements. Separating Niobium is not a simple process.
To be a stand out project means to have a large high grade preserved component of the weathered material, which CBMM at Araxa have in spades. Our neighbours in ENR have definitely found some good high grade ore, that so far looks to be in small dykes, long thin areas of only 50-100m wide.
They have no idea how far those dykes extend yet, but possibly over a couple of km. By itself what they have found so far is probably not economic. Even if we assumed a 4000m strike length, of 50m wide by 25m deep, it only comes to 8-9M tonnes of high grade mineralisation at best, and they don't have that yet.
Here at Luni we have found a resource of 2.5km long, but very importantly around a km wide of high grade material. It requires an immense amount of drilling because it extends over such a vast area. Initial resource an inferred one of 200M tonnes at 1.1% and a high grade core of 53Mt at 2.1%, is because of drilling at 200m X 200m centres initially. With infill drilling, happening now, both the grade and size, especially of the higher grade bit is likely to go much higher.
Drilling deeper at Luni would not add much value though as the grade would be lower below the oxidised body and reduce the level of the high grade, plus add complications when doing the actual processing of the ore. Oxidised ore bodies usually require different processing to fresh unoxidised ore, in other words higher costs and possibly lower overall recovery.
Luni has plenty of oxidised ore to mine for decades, which is the same as CBMM, who are mining the oxidised part and will for many decades.
You also mentioned St George in your original post, while DRE might have been a better one to compare, with their new announcement today. It's another carbonatite with limited potential as it appears to be a dyke or fissure they have found with fairly limited weathered mineralisation. Unless they find a large area of weathered material still preserved, it will be hard to prove up a viable mine.
It brings me to the last on your list SGQ. It's a very small area, an MRE and PEA have already been done on it to Canadian standards, so those documents are worth looking at. SGQ have already discounted the area where the large old tailings dam exists, so that reduces the known small resources. Extension deeper will probably go into fresh ore of lower grade than the weathered ore closer to surface. Capital cost ill be massive as we already know that processing will be very expensive from prior work.
Why would anyone spend anywhere near a billion dollars, remembering the old study had a spend of $US600M on getting to a 240k/a plant, partly because it's known the ore CBMM have is high in thorium, so extra processing is needed to lower the radioactivity of product. Here at Luni the thorium levels are quite low.
SGQ and a few others, possibly DRE is for dumb money that doesn't understand the size needed of Niobium resource or the full capital cost of building a Niobium mine. Scale matters, and here at Luni we have massive scale, and high grade, so far over 50Mt of over 2% which makes it all very viable. If the others get to that type of scale and grade, then we need to pay attention to them, but none of them come close on grade and scale.
(20min delay)