Monks who copied Bibles and other classical literature during the Dark Ages may have died of mercury poisoning. Colorful inks from various mineral pigments were used.
The bones of many Medieval monks from Danish monasteries show a previously undocumented disease called FOS. The disease caused skull lesions and was similar to leprosy. The skeletal remains containing mercury show FOS to probably be severe and similar to leprosy, and many of the clerics who died with leprosy or syphilis also showed mercury in their bones. Even those who did not die of the disease had mercury, a heavy metal, in their skeletal systems.
Mercury Contamination Sources
Mercury pollution in marine waters is a problem in the environment, since human activity has resulted in increasingly large accumulations in traveled water ways. Fish and shellfish tend to absorb the toxic metal like sponges. However this problem is a modern development, not one likely in the Dark Ages.
Living so close to the sea, fish and seafood were a staple in the Medieval clerical diet but it is unlikely that high levels of mercury from environmental pollution during that period are responsible for the fatal exposure.
Red Ink Used by Monks in Copying Manuscripts
The source of the toxin is cinnabar, the ore of the mercury metal. This mineral produces a rich red ink of a deep color which was quite popular during the the last 2000 years. The poisoned ink in the illuminated works of the incunabulum proved hazardous to the clerics’ health. Unfortunately they sometimes had a bad habit of licking their brushes with their tongues to get the proper consistency of the ink, thus transfering the toxic metal directly into their bodies.
These colorful manuscripts, called the incunabulum, date from pre-1500 C.E. But the toxin is still potent. It’s not advisable for researchers to handle or rub the illuminated parchment pages of a manuscript with their bare hands.
Other Inks used in Early Parchment Manuscripts
Mineral pigments were ground to a fine powder with a mortar and pestle and then worked in with protein binders such as egg whites to form variously colored inks. Sometimes iron oxide was used to get other shades of red or orange inks. Carbon for black and gold powder for yellow were used along with calcium carbonate (chalk) for white, copper (malachite) for green, and natural ultramarine for blue.
Cinnabar Ink in the Dead Sea Scrolls
Israeli scientists have also found red ink in the fragments of the Dead Sea Scrolls . This casts doubt on the age of the Dead Sea Scrolls. They might not be as old as previously thought since the red-colored ink was supposed to have originated in the Christian monasteries. In fact the term “Red Letter Day” refers to the clerics’ use of red ink to mark Christian holy days on the calendars.