Scientists have categorised the Earth’s rarest minerals.

None of 2,500 species described is known from more than five locations, and for a few of them the total global supply could fit in a thimble.

The researchers say it is important to hunt down these oddities because they contain fundamental information about the construction of our planet.

Some will also undoubtedly have properties that are useful in technological applications.

The list appears in a paper about to be published in the journal American Mineralogist.

It is authored by Dr Robert Hazen, from the Carnegie Institution in Washington DC, and Prof Jesse Ausubel of The Rockefeller University, in New York.