Abstract
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.
Highlights
Coronadite is a Pb-Mn hydrous oxide that belongs to the tetravalent Mn-oxide-rich mineral that belongs to cryptomelane group, which is usually associated with supergene manganese ores[1,2,3]
Petrography: The coronadite found within the profiles of Wadi Khaled occur as secondary veinlets associated within the secondary chrysocolla and apatite, as well as, thin laminations alternating with apatite and siltstone layers (Fig. 3)
The ternary plots of obtained values of Ba, K, Fe and Pb show clearly that there are no pure coronadite phase but rather hollandite-coronadite and cryptomelane-coronadite solid solutions mineral type phases (Fig. 8). This observation would clearly indicate the epigenetic mode of formation of the mineral, which is in agreement with field and petrography findings
Summary
Coronadite is a Pb-Mn hydrous oxide that belongs to the tetravalent Mn-oxide-rich mineral that belongs to cryptomelane group, which is usually associated with supergene manganese ores[1,2,3]. The tetravalent Mnoxides indicating oxidizing conditions during formation[4].coronadite is reported to form during lateralization[5]. Ehrlich et al.,[6] found manganese nodules that were composed mainly of coronadite formed by epigenetic solution. Coronadite is fairly rare mineral of the oxidation zone, is in most cases the product of simultaneous weathering of Mn and Pb-minerals; Pb-replacment deposits in Mn-rich limestones[2]. Discovered and described by[7] on ore vein in the state of Arizona, USA. Later was discovered associated with cryptomelane, hollandite, limonite, quartz and kaolinite in Morroco[8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
