RE's aren't particularly rare. It's more of a challenge to find them in concentrations where it is worth trying to filter them out. The 'supply' isn't really constrained. If prices rise enough, there are plenty of locations around the globe that would be economically viable for mining. In fact, when prices jumped several years ago, a number of newer mines were started and older ones re-opened. Then prices crashed again when the current major suppliers jacked up their production. That is as close to rule 4 as I care to get on this topic, but the reality of the RE market would allow blowing WAAAY past rule 4 territory without breaking a sweat.
So, leaving geopolitics aside, having a reasonably good concentration of those RE metals is a good start, but isn't anywhere close to determining if they are any cheaper to mine than existing sources. RE Mining requires LOTS of water and LOTS of Hydrochloric acid. Shipping those out to an island or generating them in place is no mean feat. Also, just mining the raw materials and shipping them to existing refiners is pretty darn expensive given how very little RE metals are in even the richest deposits. There is also the mix of metals available. There are two general categories of RE metals, Heavy and Light. I don't recall off the top of my head whether the ones mentioned are heavy or light. The heavy ones are significantly more profitable though. Lastly, RE mining creates some pretty nasty tailings and a butt-load of Cerium that you have to do something with. You need a decent amount of space for settling pools just to dry out all the muck you have created and then need to handle disposing of them in a manner that wont be described as an environmental disaster if someone else sees you do it!
I'm not trying to take all the wind out of your sails. It's entirely possible this really is a find that will change the industry. It's just that mineral concentration alone isn't enough to justify opening a new mine at the moment. There are other factors that generally make or break the decision no matter how awesome the ore is.
