Archaeometric analysis of the “Jehoash Inscription” tablet

Abstract

A gray, fine-grained arkosic sandstone tablet bearing an inscription in ancient Hebrew from the First Temple Period contains a rich assemblage of particles accumulated in the covering patina that includes calcite, dolomite, quartz and feldspar grains, iron oxides, carbon ash particles, microorganisms, and gold globules (1–4 μm in diameter). There are two types of patina present: thin layers of a black to orange-brown, iron oxide-rich patina, a product of micro-biogenetical activity, as well as a light beige patina mainly composed of carbonates, quartz and feldspar grains. The patina covers the rock surfaces and inscription grooves post-dating the incised inscription as well as a fissure that runs across the stone and several of the engraved letters. Accelerator Mass Spectrometry (AMS) analyses of the carbon particles in the patina yields a calibrated radiocarbon age of 2340–2150 Cal BP and a conventional radiocarbon age of 2250 ± 40 years BP. The presence of microcolonial fungi and associated pitting indicates slow growth over many years. The occurrence of pure gold globules is evidence of melting (above 1000 °C) indicates a thermal event. This study supports the antiquity of the patina, which in turn, strengthens the contention that the inscription is authentic.