I am researching the abundances of rare earth elements and rare metals in meteorite samples, because I want to investigate the notion that asteroids represent abundant stocks of rare resources. The literature on space resources speaks volumes about platinum group metals, but little about anything else, so I did my own homework. Unfortunately I have no background in mineralogy, and I cannot find data on the actual abundances (in ppm, percent, or micrograms/gram and so on) of REEs/rare metals in meteorite samples. I figure this is an appropriate place for this question, sorry if I'm wrong.

My understanding is that the abundances of non-volatile elements in CI chondrites represents the primordial abundances at the formation of the Solar system. Therefore, the REE+rare metal content of other types of meteorite, and thus asteroid rock, is generally given by comparison to the CI chondrites -- ie, how much more or less enriched they are.

The problem for me is that the CI abundances seem to be nowhere specified in ppm or any measure relevant to mining, so I have no idea how useful any of these rocks could be for evaluating asteroid ore viability. The literature on economically viable ore grades seems to specify quantities of rare elements between 0.1% and 10% per unit mass, for commercial mining. So what are the abundances of rare elements in different meteorite types in ppm/percent?


2 Answers 2


You should start with the GERM Reservoir Database. Not the easiest to use website, but the most comprehensive. You can look up elemental concentrations in all kinds of "reservoirs", including meteorites. For example, look up CI Chondrites to see the elemental values that are commonly used for REE-diagram normalisation. You can look up by specific meteorites, or averages of groups. You can see values by paper, and in most cases they also include a scan of the original data from the paper itself. Note that it's also usually good practice to actually read the paper to understand how the data were collected, analysed and what do they mean.

That said, as for your general idea of using asteroids as ore deposits for rare metals:

...because I want to investigate the notion that asteroids represent abundant stocks of rare resources.

As a rule of thumb, this works well for the PGE (platinum group elements) and related metals (Te, Au, Re). The reason is that those metals are chalcophile or siderophile, and in the Earth they are concentrated in the core and depleted in the mantle and crust. In (some) asteroids, this differentiation did not occur and the concentration of these elements is still (relatively) high in the bulk material.

However, the REE and other HFSE metals (i.e. Zr, Hf, Nb, Ta), are not concentrated in the core. In fact, being lithophile elements, they are particularly enriched in the Earth's crust. Going to mine them from asteroids will be pointless.

Here are some more questions and answers that will clarify some concepts:

Why is uranium only in the crust, really?

What is the difference between chalcophile and siderophile elements?

What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?


Table 2 of this paper lists concentrations in CI chondrites of all elements in ppm with variances. This is for one 14kg meteorite that fell in Orgeuil, France in 1868.

Check out pages 8-10 for the table and data.


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