SESSION 6 - Characterising lithic sources
Monegros-type chert: petrographic characterization and prehistoric usage

This work presents macroscopic and microscopic descriptions of around twenty outcrops located in the Monegros territory, in the Middle Ebro Basin, where this chert variety has been found, all of them of primary or sub-primary order. These descriptions allow us to define two different origins: continental lacustrine and evaporitic. This chert appears as kidney-shaped nodules (occasionally very thin, like tablets) that can be found either isolated or stratified.  Following the petrologic study, we review materials found at several archaeological sites in the Ebro Basin where this chert type has been described, usually due to the presence of Liesegang rings, easily recognisable by archaeologists.