mitchipedia:

Prussian Blue, a pigment used by Picasso in his Blue Period and for Van Gogh’s “Starry Night,” could become useful for recycling cell phone components and disposing of nuclear waste

Jennifer Ouellette:

Prussian blue is the first modern synthetic pigment. Granted, there was once a pigment known as Egyptian blue used in ancient Egypt for millennia; the Romans called it caeruleum. But after the Roman Empire collapsed, the pigment wasn’t used much, and eventually the secret to how it was made was lost. (Scientists have since figured out how to recreate the process.) Before Prussian blue was discovered, painters had to use indigo dye, smalt, or the pricey ultramarine made from lapis lazuli for deep-blue hues.

It’s believed that Prussian blue was first synthesized by accident by a Berlin paint maker named Johann Jacob Diesbach around 1706. Diesbach was trying to make a red pigment, which involved mixing potash, ferric sulfate, and dried cochineal. But the potash he used was apparently tainted with blood—one presumes from a cut finger or similar minor injury. The ensuing reaction created a distinctive blue-hued iron ferrocyanide and eventually came to be called Prussian blue (or Berlin blue).

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The pigment has other uses. It’s often used to treat heavy-metal poisoning from thallium or radioactive cesium … Prussian blue helped remove cesium from the soil around the Fukushima power plant after the 2011 tsunami. Prussian blue nanoparticles are used in some cosmetics, and it’s used by pathologists as a stain to detect iron in, for example, bone marrow biopsy specimens.

Picasso’s favorite pigment may one day recycle metals from your cell phone