Geological fieldwork in Burkina Faso
In the framework of the project “Women Food Entrepreneurs in Kenya and Burkina Faso: Building inclusive business models for food security in the city slums of Kisumu and Ouagadougou” a geochemical survey was carried out in Burkina Faso in order to find rocks suitable for producing powder for soil conditioning. The survey was carried out in the period October 25 to November 2, 2016 by Dr Janvier Kini and Huig Bergsma.
The study was focused on rocks that could be used as soil conditioner in a zone no more than 100 km from Ouagadougou. The same approach was applied in Kisumu in August.
Although the area immediately surrounding Ouagadougou is underlain entirely by granite, east of Ouagadougou a S-N oriented zone of volcanic related rocks runs which bents eastward and curls around north of Ouagadougou. As far as the mining industry is concerned, Burkina Faso is well known for its gold and base metal (Cu, Zn, Ni) mining. Dimension stone and gravel are mainly produced in granite, laterite and clay quarries. Unfortunately, these rocks are not very suitable for the production of agricultural rock dust. Fortunately, we managed to locate two tuf quarries near Boussouma, one of which active, the other abandoned. Tuf is a very friable rock that sometimes contains zeolites, a well-known soil conditioner. In the same area two outcrops of calcium and magnesium rich basalts were found (Tamiga and Lougouma), indicating a potential for future rock dust production. Although granite may not seem to be a very useful rock at first glance, it was decided to sample some biotite containing granite outcrops. Biotite is a K-rich mineral frequently found in granites and a very efficient fertilizer. The most promising samples were taken in a very large artisanal quarry named Pissy, where 5 cm large biotite flakes were found by just walking around. In this quarry many women and children work under harsh conditions. If a sufficiently rich biotite concentrate could be produced from their sand product, it could be sold as a local alternative to expensive potash fertilizers.
All together 17 locations were sampled and analysed by Handheld XRF, 5 of them were taken to the Netherlands for further analyses and experiments.