They specifically chose the Archean North Atlantic Craton because it hosted the oldest known deposits of the gemstone. The research team was delighted to have such a rare discovery on their hands.

Evidence for a long-lived active margin on the Archean Wyoming craton. Geological Society of America Bulletin, 112, 564-578. Chamberlain, K.R., Frost, C.D., and Frost, B.R. (2003) Early Archean to ...

The broader belt spans 1200km along the southern margin of the Archean Yilgarn craton, with Terrain maintaining that recent airborne geophysical surveys demonstrate compelling evidence that the ...