Research Story by Jonathan Seyfried

History PhD Student at the University of New Mexico

Posted: August 10, 2025

Why did Matha Armagnac drink pulverized gemstones?

In the spring of 1375, Matha d’Armagnac, the Duchess of Girona, drank a solution made with pulverized emeralds as a key ingredient. If the gemstones worked as predicted by the apothecary, Matha’s pregnancy would result in the birth of a strong boy. In preparing the mixture, the apothecary, named Johan Davallano, learned the appropriate quantities of gemstones, but he also needed to trust the supply chain that brought the ingredients to his shop.

The idea for this paper came to me last summer as I read Josep Roca i Heras’s 1929 biography of Joan I of Aragon. Roca i Heras, in his discussion of Joan’s marriage to Matha Armagnac, explained that Matha’s first child, born in June 1374, died within a few months. This experience led her to a more aggressive pharmaceutical regimen during her second pregnancy, including the potion made from precious gems.¹ I located the archival source, which you can see here, a payment record to Johan Davallano dated June 1, 1375.

Looking at this record up-close, we can see Davallano’s name on the first line and then midway through, the price of thirty solidis for the first “polvora cordial en que entraren perles, safirs, maracdes, e altres pedres precioses.” I chose emeralds from this mixture for my study but I would certainly find interesting comparisons tracing the pearls and sapphires as well.

In reading I had done previously about Joan I of Aragon, I knew that as Duke of Girona and later as King, Joan ingested water steeped in unicorn horn and possibly scrapings from it too. Unicorn, which we now know was actually narwhal tusk, possessed a reputation in the Late Middle Ages as a supremely powerful cure-all. My PhD Advisor, Michael A. Ryan, has argued that Joan’s pursuit of unicorn horn played into a larger Mediterranean-wide spiritual economy that paralleled that of relics.²

The Research Question: How did medieval apothecaries and merchants construct medical knowledge?

I wondered how Johan Davallano obtained the emeralds used in the potion for Matha and how Joan developed his understanding of the medical properties of unicorn horn. How did these commodities travel through trade networks to arrive in their hands? What kinds of documentation or relationships authenticated these substances as genuine? I had read two books that seemed to each provide half of the answers to these questions: Out of the East: Spices and the Medieval Imagination by Paul Freedman and Trade, Trust, and Networks: Commercial Culture in Late Medieval Italy by Gunnar Dahl.

Since both emeralds and unicorn horn came at high prices due to their rarity, I needed a more available substance as a useful comparison for my question about the construction of medical knowledge. Sugar came to mind, since during the Middle Ages it straddled the boundary between cuisine and medicine. Also, sugar arrived to the Mediterranean only in the Middle Ages; the ancient Greeks and Romans had used honey as their primary sweetener.³

Three Commodities, Three Pathways to Medicine

Sugar

Since the volume of sugar traded medieval Europe far outnumbered that of emeralds and unicorn horn, much more documentation exists. Much medieval documentation attests to the arrival of sugar into medicinal discourse in the medieval period. Sugar was unknown in the Mediterranean during ancient times. The Greeks and Romans used honey as a sweetener. Sugarcane cultivation in Sassanid Persia diffused throughout the Muslim world after the Umayyad conquest in the seventh century. The Persian word šakar forms the basis for the Arabic sukkar, medieval Latin saccarum, and all the vernacular variations.⁴ Sugarcane cultivation spread and its growth as a commodity steadily increased throughout the Middle Ages.

By the fourteenth century, Francesco Pegolotti’s merchant handbook contained thirteen varieties of sugar.⁵ The account books of a Barcelona apothecary, Francesc de Canes, demonstrate that by the Late Middle Ages, sugar had entirely triumphed over honey as a sweetener.⁶ The answer to the question on this slide, for at least some regions of the Mediterranean, is that sugar became medicine almost immediately upon its arrival. As we shall see in a moment, however, the status of sugar as a medicine versus culinary sweetener varied across time and place.

We might readily recall the classic line from Mary Poppins, “a spoonful of sugar makes the medicine go down.” Sugar by itself rarely appears as a recommended medicine. However, the idea that something tasty possessed beneficial health qualities fit nicely within the humoric medical theories of the time. Thus, sugar became a key ingredient in medicinal syrups and electuaries. Muslim scholars in Al-Andalus, such as Ibn Baytar and Al-Zahrawi led the field of pharmacology and their recipes featured sugar ubiquitously.⁷ However, in the thirteenth century pharmacopoeia written by Minhāj al-dukkān, a Jewish pharmacist in Mamluk Cairo, sugar appears with equal emphasis for cuisine and medicine.⁸ Likewise, in the Cairo Genizah, sugar appeared as a key ingredient in pharmacy lists, but also listed alongside culinary spices in several merchant communications. However, this varied across different localities. Freedman notes that in the fourteenth century the English used sugar extensively in cooking but the French considered it a medicine.⁹

For sugar, evidence exists for the intertwining of commerical ties and transfer of its medical uses. In Barcelona, we see the trade networks of merchants and apothecaries tightly woven together. Apothecaries such as Bartomeu Saragossa and Francesc de Camp had sugar refining equipment in their inventories and established relationships with merchants as well as masters of sugarcane cultivation such as Niccolò de Scicli.¹⁰ Likewise, evidence of the close connections between apothecaries and merchants pervades the records of England’s Royal Apothecaries, in which the wholesalers often blend with retailers.¹¹

Emeralds

For emeralds, the documentary evidence offers us a different perspective on the process by which a commodity twisted its way through medical discourse. Medieval medical theories supported the notion that minerals grew from a seed and that the humoral quality of a stone would intervene in the likewise humoral origin of a disease. For centuries, the origin of emeralds in premodern Europe was thought to be Egypt and Austria, but isotope analysis carried out in recent decades has revealed that much of the extant emerald supply from the ancient world, such as that in these earrings, came from the Swat River Valley in Southwest Asia. No recipes exist in ancient sources for ingesting pulverized emeralds, but they did develop a reputation for ophthalmic benefits. A long-term legacy of this belief continued into the modern era with traditional bankers’ desk lamp made with a green stone shade.

Isidore of Seville drew from Pliny the Elder when he instructed his readers on how to oil the emerald to enhance its curative properties for diminished eyesight. Isidore also complained about the prevalence of fake emeralds, revealing that the supply chain lacked consistent methods of authentication. By the twelfth century, Hildegard of Bingen’s lapidary identified the emerald as a way to prevent plague, a cure for stomach ailments and an antidote to poison. Around the same time in Seville, a prominent physician, Ibn Zuhr, also lauded the emerald as an antidote to poison. The famous response of the Medical Faculty of Paris to the Bubonic Plague in the fourteenth century featured emerald as a cure to the plague and thereafter emeralds became the most common gemstone of those recommended in plague treatises. Late medieval works focused on the properties of gemstones, called lapidaries, connected the emerald to cures of many ailments and many lapidaries, such as those of King Alfonso the Tenth and Jean d’Outremeuse, recommended ingestion of it in pulverized form. Yet despite all of this, the Cairo Genizah mentions of emerald number only six and lack any medical context, not appearing on any of the pharmacy lists. The merchant handbooks consulted for this study, such as the Zibaldone da Canal and Pegolotti’s Practica della Mercatura, mention emeralds but without any hints of medicinal use.

Unicorn Horn

Eventually, by the end of the sixteenth century, the trade in unicorn horn picked up and it routinely appeared in the records of bourgeois apothecaries, albeit in small quantities. However, at the time of Joan I of Aragon in the Late Middle Ages, narwhal tusks entered into Mediterranean trade networks very rarely.

Based on modern knowledge of narwhal habitats and migratory patterns, Xavier Dectot has identified Disko Bay on the west coast of Greenland as the only likely source for narwhal tusks for premodern Europeans. The narwhal migrate southward to this location every winter, but according to archeological and documentary evidence medieval Norse Greenlanders journeyed to Disko Bay only in the summer. Thus, the source for narwhal tusks could only have been the washed-up remains of dead narwhal that the Norse Greenlanders found. This increases the plausibility that from the very start of the supply chain, those who traded in narwhal tusks earnestly communicated them as, if not unicorn horn, then at the very least the remains of fantastic beasts from a far away land. Indeed, the tusks, which could grow up to fourteen feet long, have a swirl texture that appears otherworldly.

From there it is reasonable to speculate that the tusks entered into a trade network of the most precious objects, handled by specialist merchants like those alluded to by Zohar Amar in his discussion of gemstones. By the time the unicorn horn arrived to Joan, it had probably passed through the hands of several elite actors. Unliked sugar or emeralds, unicorn horn never became an ingredient. It was always powerful all on its own. Its immense value caused it to quickly exit merchant channels and then it got transported through elite networks of exchange, typified by Joan’s gifting of some to the Avignon Popes. The below image is the second page of Joan’s 1393 letter to the Avignon Pope, Clement VII.

The prestige of unicorn horn continued until the advent of modern science. By the fifteenth century more records emerge of unicorn horn products in the inventories of the members of European royal families and other elites interested in the most glorious conspicuous consumption. The legacy of this most prestigious of objects reverberated through subsequent centuries. The royal throne of Denmark contains several large pieces of narwhal tusk.

Conclusion

Merchants and spicers were indeed agents of medicinal knowledge transfer for sugar, but less so for emeralds and unicorn horn. For emeralds, all signs point to a similar operation of trust through trade networks, like those described by Gunnar Dahl, but too specialized to have left much of a documentary record. For unicorn horn, however, the spicers and apothecaries got cut out of the equation. Elite actors transported this commodity of highest prestige and transferred knowledge of its properties.