ABSTRACT
Halloysite was named by Berthier in recognition of Belgium geologist J.J. d’Omalius d’Halloy (Daltry and Deliens, 1993) who, in the early nineteenth century, collected samples of waxy, white clay at Angleur, Liége, which Berthier (1826) later analyzed and described. While the type locality for the Angleur halloysite has long been lost, Dupuis and Ertus (1995) assert that original descriptions clearly identify the clay as having been recovered from karstic cavities within Dinantian (Lower Carboniferous) limestone in association with Pb and Zn sulfides, and the products of sulfide weathering. Similar occurrences have been described from various buried karst on the Entre-Sambre-et-Meuse plateau in southern Belgium, and also at Aïn Khamoudain, Central Tunisa, and the Djebel Debbagh region in northeastern Algeria (Perruchot et al., 1997; dePutter, 2002; Dupuis et al., 2003; Renac and Assassi, 2009; Bruyère et al., 2010). The formation of relatively pure masses of halloysite close to where the fluids have interacted with carbonate rocks is common to these and other important halloysite occurrences, as described below. Substantial volumes of halloysite-rich clays also result from weathering or hydrothermal alteration of aluminum silicates in other geological settings, the most significant being the alteration, under neutral to acidic conditions, of Cenozoic volcanic deposits.
