G. Bardossy and J. M. Fontbote
Observations on the age and origin of the reported bauxite at Portilla de Luna, Spain
Economic Geology and the Bulletin of the Society of Economic Geologists (November 1977), 72(7):1355-1358

Abstract:
A previously published paper (Font-Altaba and Closas, 1960) announced the discovery of Devonian bauxites in the vicinity of Portilla de Luna, province of Leon, Spain. With the results of their field and laboratory investigations the present authors demonstrate that no bauxitization took place during the Devonian period in this region. The material previously described is not a bauxite, but a minor occurrence of gibbsite with lithiophorite, halloysite, and goethite in joint fillings and pockets. These minerals are products of the secondary oxidation of the Devonian shales. It is virtually certain they did not form before the end of the Miocene, and most likely they are of Quaternary age.