Mineralogical and petrographic study of tuyères from Pongsolo (Lekie, Central Cameroon)

Pongsolo is located in the Lekie Division of Central Cameroon. Archaeological studies have confirmed the presence of iron smelting activities at this site between the 15th and 16th century AD. Eight fragments of tuyères from Pongsolo were analysed by X-ray diffraction and polarised optical microscopy to determine their mineralogy, and deduce their firing temperature and the iron smelting temperature. Five tuyères are reddish with some black parts on their surface, whereas the three others are black and covered with a layer of slag. X-ray diffraction revealed three mineralogical groups of samples: The first group (2 samples) contained quartz, muscovite and kaolinite. The second group (3 samples) contained muscovite and quartz and the third group (3 samples) contained mullite and quartz. The results of polarised optical microscopy agree with the mineralogical groups. The first group is characterised by a reddish matrix with an abundance of mica flakes (biotite and muscovite), indicating a firing temperature range below 600 °C due to the presence of kaolinite. The second group has a dark matrix with few mica flakes, indicating a temperature range of 600 to 900 °C. The third group is characterised by a vitrified matrix, indicating a firing temperature above 1000 °C. The variation of the mineralogy and the firing temperature of the tuyères can be explained by their different position in the furnace. The presence of mullite, vitrification, quartz and a layer of slag in the third group indicated an iron smelting temperature between 1000 and 1300°C.

   This work is licensed under a Creative Commons Attribution 4.0 International License.