Sometimes It Pays to Look Back

My featured story this week on my “World’s Oldest Stuff” blog is about an ancient artificial pigment called Egyptian Blue. This pigment has a unique property which is now being investigated for use in modern applications as varied as specialized inks and medical imaging.

Egyptian Blue is an artificial pigment which most experts believe was first created in Egypt more than 4,500 years ago. At some point in time, researchers discovered that when a red light is applied to the pigment, it reflects infrared light. Museum conservators and archaeologists have taken advantage of this unique property to spot fake artifacts and to verify others for more than ten years. Now other researchers have made new discoveries about this ancient coloring agent.

A team of chemists at the University of Georgia studying Egyptian Blue’s primary molecule, calcium copper tetrasilicate, have discovered the pigment can reflect infrared radiation even when reduced to the thickness of a single layer a thousand times thinner than a human hair. Now they’re busy dreaming up uses for this discovery.

Tina Salguero, a member of the University of Georgia team, believes the calcium copper tetrasilicate could be used in medical imaging applications since infrared radiation can easily pass through human tissue. Other possible applications might include new types of security inks used to prevent the forgery official documents and paper currencies. Other potential applications for the molecule involve possible uses in LED and optical fiber technologies.

Both LEDs and optical fibers transmit signals using infrared light. Since calcium copper tetrasilicate works so well in extremely tiny quantities, it might be possible to further miniaturize electronic components, for example.

Did the ancient Egyptians know about the unique reflecting properties of Egyptian Blue? Unless they had some way of producing red light, the answer is that they probably did not. But we keep finding out that the ancient ones knew things we are only now discovering. Personally, I wouldn’t put anything past them.

Archaeology’s website is at

If you’d like to read my article about the "World’s Oldest Pigment," go here