France, July 3 -- Teeming documents charting the rich subsoil of what is now the Democratic Republic of Congo fill nearly 500 metres of shelving at the AfricaMuseum in Tervuren, outside the Belgian capital.

The museum has pledged to digitise the contents and make them public within five years - and as the race for so-called rare earths heats up, it has grappled with how far to share the data with the mining sector.

Last year, the institution - formerly the Royal Museum for Central Africa - turned down an offer from the US company KoBold Metals to handle the archive's digitisation.

Instead, with significant EU funding, it intends to appoint a European contractor for the mammoth project, currently in its preparatory phase.

The aim is ul...