Archaeometric and archaeological characterization of the fired clay brick production in the Brussels-Capital Region between the XIV and the third quarter of the XVIII centuries (Belgium)

Abstract

Brick samples from different archaeological sites represent mostly houses in Brussels (Belgium) built between the end of the Middle ages (end of 13th-beginning 14th centuries) and the end of the Modern Period (18th century). The study gives a mineralogical–petrographical–chemical characterization of the brick samples made in the Brussels-Region and sources the raw silty material, the moulding sand and the lime-mortar. Optical microscopy, X-ray powder diffractometry, Laser Ablation Inductively Coupled Plasma Mass Spectrometry, magnetic susceptibility and scanning electron microscopic with an energy dispersive X-ray attachment were applied both to fired clay bricks and regional clayey materials. Bricks were moulded with a silica rich, non-calcareous loam gathered locally in the alluvial plain of the Senne valley. Material from gleysols and fluvisols were mined separately to shape two types of bricks. A strong chemical resemblance with the thick loessic deposits of the Belgian plateaus results from erosion and river transport and sedimentation in the wide alluvial plain of Brussels. Petrography and geochemistry show minor participation of marine Lower Palaeozoic, Cretaceous and Tertiary rocks from the alimentation area of the Senne. Although clayey tertiary layers outcrop in the Brussels Region and are cut by the numerous tributaries of the Senne valley, they were never exploited for brick making in the Brussels Capital Region. Mineralogical composition and petrography suggest the absence of mixing with river sand or local marine tertiary sands. Local sediments extracted in the valley sides as Eocene fossiliferous fine sand were used as moulding sand.