There seems a lot discussion around REE and land configurations (particularly relating to 'mineral' traps and weathering). In geological structures (particularly where you are referring to weathering and leaching), natural traps (i.e. lets call them craters - but they can also be slopes of land where the trap is a rock type that is not easily weathered trapping leached minerals from other rocks that have weathered) do accord with where you can get a concentration of a mineable mineral (clearly VMM and MEI are examples here where a 'trap' has been identified and assays have been good).
Now the whole area itself hasn't been appropriately explored and there will likely be other similar structures around (and it doesn't have to be a crater as some like to refer to it as a natural trap). It is all about weathering, water run off and how a resource in this space is trapped in concentration in a defined area.
IMO there is also a lot of confusion around what grade of resource is viable - it depends on the resource type that hosts the REE. Ionic, you see things on the ASX where companies are saying anything less than 0.1% (1000 PPM) is viable - just look at IXR.
ENV has a large land holding - it needs to explore to determine what it has. It is pretty simple. Clearly in the right area but time will tell what the drilling does. I have a small investment here - it is about risk/reward that is it.
The below is just an information dump from other posts - hopefully they may help others understand REEs and rock/resource types.
IAC resource:As I posted previously,
I suspect ENV are pretty confident they have an IAC resource in its tenements - it is a question of extent and what proportion of the resource is actually ionic and what proportion is clay - there is no such thing as a 100% purely ionic resource btw is my point.But yes they can't confirm anything until they do the METs, and based on a previous Ann suspect they will do that low cost test one is talking about here on some of the augur samples I suspect. Geologists know what they are looking at is my point.Now the key aspects are as follows - noting ionic clays are essentially the weathering and release of REEs from a previous hard rock deposit:1. The extent of resource where a simple pH4 solution can be used (essentially a low cost almost salt type solution that allows capture of REEs), and that in part defines it been IAC. This is essentially what makes an ionic resource - well the cheapness in extraction methods if have enough of it.2. From there the extent of secondary resource where a stronger pH (meaning more acidic ) solution is required (essentially adding a minor amount of acid to attain the REEs but the risk is if need too much acid results in impurities and lower REE prices been received from downstream converters - also added cost might make it unviable to extract). And that is where grade is important - where you have low grade, well you need more of the resource to be ionic with the secondary resource (i.e. I will term that as clay not going to Step 1) not requiring say too much of a difference to pH4 in simplistic terms, meaning it is almost ionic3. The extent of resource that has not been broken down - in simplistic terms weathering has not been complete - cannot be recovered if using an ionic process. That is won't be recovered. That is why for hard rock deposits you need a higher grade than ionic resources.Some background info on resource types below:It is also difficult comparing process flowsheets in any event as REE deposits are always unique given REEs are 17 elements and their composition does differ between deposits and how, for example, you use specific gravity for recovering each element in a flowsheet and that can also differ depending on the extent of what you are really seeking to recover on a per REE element basis.
The most valuable rare earths are IMO dysprosium (for one used in control rods in nuclear reactors for one and is also as an alloy for neodymium based magnets among other uses) andNeodymium and Praseodymium (i.e. the latter two for EVs btw). In other words the viability and cut off grades for your rare earth project is in part based on how much of these minerals, IMO, are in the %REE in your deposit. The others are also important btw as well but I think these three are the key ones, but I recognise others may have an opinion
https://www.mining.com/the-only-five-rare-earth-elements-that-matter/
Refer:http://australianminingreview.com.au/commodity-focus-ndpr/
,,Page 10 of this article - page 10 is a very interesting read as well.
https://www.mdpi.com/2075-163X/7/11/203/pdf - although old shows average grade of deposits that were slated for development a while back (Longnan in China I think is a IAC deposit btw).
I will also simply say a REE clay deposit is very different to a hard rock REE deposit, and even REE hard rock deposits are very different depending on what is the host ore, because processes also differ depending on the ore type. There is little/limited bonding of the REE to clay as against REEs in hard rock, hence why opex costs are considered lower for clay deposits, and they are even lower for IAC deposits, meaning separation is a lot easier as well at the beneficiation stage, which allows improved ability to separate minerals, say through using their specific gravities for example from the gangue, to then move to the other aspects of the process flowsheet. This pic from BioLantanidos explains that best too me-http://www.hochschildmining.com/en/exploration/greenfield_exploration/biolantanidos
That is the beneficiation stage is a lot more straight forward for clays when compared to hard rock for REEs is the point, which then aids costs further downstream as well, but is still relatively complex.
Mining rare earths is environmentally sensitive as we all know, and always has been, i.e. just ask LYC especially around processing and their transport, but mining itself does deal with environmental issues so time will tell how IXR (and the host of prospective REE deposits) address these issues.Hard rock REE need to have higher % of REEs than clays and ionic even less % to be viable.
Ex cerium?I suspect a key issue is how you sell your REE concentrate as well. Is it ex-cerium??In brief, you can more easily remove cerium from rare earths because it is relatively stable in oxidized form, with the other elements then recovered by solvent extraction by and large. The question is where in the process does this happen?https://www.researchgate.net/publication/309342584_Cerium_Separation_from_Light_Rare_Earth_Concentrate_by_Liquid-Liquid_ExtractionIn addition, cerium in the rare earth solution that goes to separation facilities can act as a 'penalty' hence you want to be removing this before your sales to 'Separation' facilities and obviously sell what cerium you recover yourself - i.e. your customers that separate the rare earth elements from the solution.https://link.springer.com/chapter/10.1007/978-3-319-95022-8_233
===REE to oxides For those that like cheat factors this link shows you the conversion factors for converting elements to oxides:
https://www.jcu.edu.au/advanced-analytical-centre/services-and-resources/resources-and-extras/element-to-stoichiometric-oxide-conversion-factors
For those seeking to understand the conversions they are individually based and you have to work within this formula you attain for each REE and how it converts to oxides.
Example: Take Lanthanum and convert to an oxide using this link:
https://www.convertunits.com/molarmass/La2O3
The “factor” equates an elemental assay to an oxide concentration for each element:
Relative Atomic Mass (La) = 138.9055
Relative Atomic Mass (O) = 15.9994
Total molecular weight of La203 = (2x 138.9055 + 3x 15.9994)) = 325.8092g/mol
Oxide Conversion Factor = 1/((2x 138.9055)/(325.8092)) = 1.173
For an example of how to go from assays to TREO and from there basket prices and how many tonnes you need to make 1kg TREO refer Post #: 65423696
A bit of a dump, but it is all about risk reward here, in an area that has not been largely explored and mapped. Clearly VMM and MEI are more progressed than ENV who has yet to show assays and fully drill their tenements. End of story - either investors here will lose the lot or make a lot, and it is how this side of the market works. Free carry where you can.
Anyway, may comment later on when there is something to comment on - i.e. assays and METs, and by METs I mean a number of METs over a large part of the deposit.
All IMO 
(20min delay)