Natron as a flux in the early vitreous materials industry: sources, beginnings and reasons for decline

Documented natron sources and their medieval decline

what the source states

Wadi el Natrun and al-Barnuj are identified as the primary ancient Egyptian natron sources for the vitreous-materials industry, with a documented decline and replacement by plant ash in the 7th–9th centuries AD.

what we infer

Establishes ingredient availability at scale and a documented supply discontinuity — the kind of discontinuity a lost-craft narrative needs, though the paper itself makes no claim about stone.

limitations

• The paper concerns glass and faience; it says nothing about stone-making.