the research history of Egyptian blue provided natural scientific evidences for the production in the northern Phlegraean fields (agreement with trace minerals found in the beach sands at the Gulf of Gaeta), the use of a sulphidic copper ore (instead of often-mentioned metallic copper or bronze), and plant ash as flux in the raw material mixture. Furthermore, indications for a synthesis predominated by solid state reactions were found, while the melting of the raw materials into glass most likely played a negligible role. A follow-up study on Roman Imperial pigment balls excavated in Aventicum and Augusta Raurica (Switzerland; first to third century AD) confirmed the results in 2022. The consistent composition of around 40 identified minerals establishes a connection to the northern Phlegraean Fields; a sulphidic copper ore and plant ash have also left their marks. Thus, the Roman production monopoly probably existed for centuries. In addition, the analyses revealed unwanted by-products of the synthesis, locally limited to micorparticles on the sphere's surfaces, which can be traced back to suboptimal burning times or mixing ratios, respectively: a cuprorivaite with crystal defects in its layer structure and a copper-bearing green glass phase, characterised by Raman spectroscopy for the first time. Modern applications Egyptian blue's extremely powerful and long-lived infrared luminescence under visible light has enabled its presence to be detected on objects which appear unpainted to the human eye. This property has also been used to identify traces of the pigment on paintings produced as late as the sixteenth century, long after its use was presumed to have died out. The luminescence in the near-infrared, where neither fat nor hemoglobin show high absorption coefficients, in conjunction with the capacity of Egyptian blue to delaminate by splitting into nanosheets after immersion in water, also indicates it may have several high-technology applications, such as in biomedicine (e.g. bioimaging), telecommunications, laser technology, and security inks. Researchers at the Lawrence Berkeley National Laboratory discovered that Egyptian blue pigment absorbs visible light, and emits light in the near-infrared range. This suggests that Egyptian blue pigment could be used in construction materials designed to cool rooftops and walls in sunny climates, and for tinting glass to improve photovoltaic cell performance. See also Blue pigments References Further reading Dayton, J. 1978, Minerals, Metals, Glazing & Man, or, Who Was Sesostris I? London: Harrap. . Lucas, A. & Harris. J.R. [1948] 1999, Ancient Egyptian Materials and Industries. Dover books