COOPERATION, COMPROMISE, AND CREATIVITY: EXPLORING FOR DIAMONDS IN THE SAHARA DESERT OF ALGERIA

On January 1, 2017, the U.S. Geological Survey (USGS) and the Algerian Geological Survey Agency (ASGA) signed a Memorandum of Understanding Project Annex to undertake a cooperative assessment of the mineral and water resources of the Eglab region. The intention is to increase the understanding of the geology and mineral resources of a remote part of the Sahara Desert in SW Algeria, to increase the geological capacity of ASGA, and to develop data and publications that will attract interest in Algeria’s mineral development. For over 3 decades, the USGS has been developing techniques to evaluate mineral resource potential—a process that incorporates geologic mapping, economic geology, geophysics, exploration geochemistry, remote sensing, mineral deposit models, and GIS analyses—and is bringing this expertise to the assessment.

The first field campaign, April-May 2017, included 28 geologists (7 from the USGS and 21 from ASGA or other Algerian agencies) that worked in 6 discipline-based teams. The exploration geochemistry team evaluated the suitability of various sample media as guides to concealed mineralization and collected kimberlite-indicator-mineral (KIM) samples for diamond exploration. However, the team had strong, differing methodology opinions over KIM sampling methods. There were advocates for 3 different methods: a heavy-mineral-concentrate method used in the United States, a deep-hole method preferred by geologists that had worked with DeBeers, and a surface-scrape method preferred by geologists that had worked with Russian exploration teams. Although there was the option for the team lead to choose the project collection method, we opted for compromise.

First, we eliminated the heavy-mineral-concentrate method as it was least appropriate for samples with a large eolian fraction. Then we modified the deep-hole and surface-scrape KIM methods and combined them into a hybrid method. Finally, we converged on an appropriate range of sieve sizes. The only remaining issue was that the available sampling equipment was designed for the heavy-mineral-concentrate method. This was solved with some creative ingenuity. We will continue to compare and test this hybrid KIM method both in Algeria and in the United States.