Mineralogy and Chemistry of Coronadite from Middle Cambrian Manganese Deposits at Wadi Dana, Southern Jordan

Coronadite was reported from the upper-most horizons of the Middle Cambrian sediments at two locations in Wadi Dana, central Wadi Araba and Jordan. The unit is composed of dolomite, limestone and shale. Geochemical investigations show appreciable variations in Mn, Pb, Fe, K and Ba contents in the coronadite between the two studied sites. Pb was found to increase downward in both sites in spite of the lateral distance between them. Fe does not vary vertically, but its concentration decreases eastward. This can be attributed to the nature and mobilization direction, duration of the process, as well as the mechanism of both Fe and Pb bearing solutions. Mineralogical analysis has revealed the presence of hollandite-coronadite, cryptomelane-coronadite and psilomelane-coronadite in solid solutions. These petrographical and geochemical characteristics of the coronadite-bearing samples indicated that they formed epigenetically.