The morphological, physico-chemical and mineralogical characteristics of the fersiallitic soils developed on basaltic lapillis rich in glass, in the Canary Islands, are herein studied. They are morphologically differentiated from the fersiallitic soils developed on phonolitic ashes in the same climatic zone by a deeper red colour, more limous texture and a hardly developed structure. These soils are rich in bases, specially on the horizon of lapilli alteration, with high contents of Fe2O3 and TiO2 and relatively low silica values, which indicates a great alteration and geochemical evolution. The mineralogy of the sand fraction shows an almost general alteration on these soils, leaving only some resistant minerals such as magnetite. Iron oxydes and hydrosydes (hematies and gothite) and aluminium (gibbsite) can be easily identified in the clay fraction, as well as a clear predominance of clays 1:1 on the 2:1.

Peer reviewed