Egyptian Blue (EB), first made more than 5,000 years ago, is the world’s earliest synthetic pigment. It is based on the blue mineral cuprorivaite (CaCuSi4O10), related to barium copper silicates also known from antiquity as Chinese blue and purple.

To fabricate EB, artisans heated sand, lime, copper minerals, and alkali to create a brilliant blue thought to symbolize eternity and the heavens, and used to adorn tomb walls, statues, and pottery. Later, Romans used it in mosaics, frescos, and buildings. Its use declined after 600 CE but survived into the Renaissance.

Rediscovered in the 19th–20th centuries, cuprorivaite was shown to have unique optical and magnetic properties, making it promising for modern applications in biomedicine, telecommunications, lasers, and security inks.

Recently, our group at Washington State University, with the Carnegie Museum of Natural History and the Smithsonian Museum Conservation Institute, recreated EB to uncover the science behind its color, ranging from gray or green to deep blue. We produced 12 versions of EB and compared them with artifacts using advanced X-ray techniques, spectroscopy, and quantitative color measurements. We found EB is a complex mixture of phases, with hue controlled by particle size, glass content, and cuprorivaite–silica ratios. Even small changes in materials or heating could dramatically shift its color.

These findings reveal ancient craftspeople as skilled materials scientists. Beyond cultural insights and conservation, Egyptian blue’s infrared glow continues to inspire modern technologies, linking past creativity with future innovation.

Email us at arce.dc.news at gmail dot com for a link to register for this online event.

Our talks typically last an hour—50 minutes for the lecture, 10 minutes for Q+A.

Alert: We do not allow recording or imaging of our presentations in any way.

Dr. John S. McCloy is Professor and Director (Department Head) of the School of Mechanical & Materials Engineering, and Lindholm Endowed Chair in Materials Engineering, at Washington State University (WSU). He is a joint appointee at Pacific Northwest National Laboratory (PNNL).

His professional career includes academia (WSU, 12 years), national laboratory (PNNL, 5 years), and industry (Raytheon, etc., 10 years).

At WSU, he leads the Nuclear, Optical, Magnetic, & Electronic (NOME) Materials Lab, and the Crystals and SemiConductors (CASC) group, both within the Institute of Materials Research (IMR). These groups develop materials solutions for energy, environment, and security applications.

Over the course of his career, Dr. McCloy has worked on diverse engineering problems, including cryogenics, composite structures, telescopes, optical ceramics, magnetic nanoparticles, ancient materials technologies, nuclear fuels, single crystal growth, and glass development for optics and immobilization of radioactive waste.

He holds degrees in Materials Science & Engineering (MSE) from the Massachusetts Institute of Technology (BS) and the University of Arizona (MS, PhD), as well as an MA in Anthropology from Arizona. He is co-author of more than 300 journal articles, book chapters, conference proceedings, public reports, and patents. He is a Fellow of the American Ceramic Society, a Fellow of SPIE (the optics and photonics society), an elected member of the Washington State Academy of Sciences, and a Fulbright Scholar.