Rare iron-bearing rocks, potential precursors as raw materials for pigments in archaeology

Abstract

From a geochemical and mineralogical point of view, iron-rich materials do not constitute real deposits but are found as rare inclusions in the carbonate, in the marl of clay formations or pebbles in marine terraces. These minerals have different origins and compositions; they are ankerite, ferroan dolomite and goethite, and substances produced by iron bacteria. The thing they have in common is that they all contain iron in modest to high quantities. These rare minerals and the fact that they are often not present in geological maps and literature often lead to them being overlooked in the search for the raw materials that led to the production of ochre pigments used in prehistoric contexts. The aim of this work is the search for potential raw materials used as a pigment for a red band painted pebble, found when a surface survey in Contrada Mandrascava (Agrigento, Sicily).  Since in the area, there are no deposits of iron minerals, we documented and described rare findings of ferruginous colouring materials found in the area.