This paper documents a new channel of the natural resource curse: the fragmentation of identities, between ethnic groups and nations. We combine individual data on the strength of ethnic – relative to national – identities with geo-localized information on the contours of ethnic homelands and on the timing and location of mineral resources exploitation in 25 African countries, from 2005 to 2015. Our strategy takes advantage of several dimensions of exposure to resources exploitation: time, spatial proximity, and ethnic proximity. We show that the strength of an ethnic group identity increases when mineral resource exploitation in that group’s historical homeland intensifies. This result holds independently of the impact of resources on local economic conditions and conflicts. We then investigate the various potential channels of transmission. Our findings suggest that feelings of economic deprivation and political exclusion associated with natural resources exploitation drive their impact on the strength of ethnic identities.