# The precious stones

**Fragmenta pretiosa**

**Known today as.** Ground sapphire, emerald, jacinth, garnet, and topaz, as they were used in medicine.

Kind: Mineral

## What was it used for?

Cordials of great price: powdered into confections to strengthen the heart and resist poison.

## What does modern science say?

Inert; their value was in their cost and their symbolism.

## Pharmacognosy and toxicology

- **corundum**: aluminium oxide, in ruby and sapphire
- **beryl**: beryllium aluminium silicate, in emerald
- **zircon**: zirconium silicate, in hyacinth
- **garnet**: 

**Mechanism.** The “fragments” of the cordial powders are among the hardest and least soluble substances known: they pass the gut unchanged and deliver nothing to the heart. The beryllium of emerald is toxic only as a dust in the lungs, which a confection does not reach.

**Dose.** Inert.

**Standing.** The electuaries that held them, like the confection of hyacinth, were the most expensive placebos of the pharmacy.

## What lore surrounds it?

See [the confection of hyacinth](https://thethinkingpress.org/materia-medica/confection-of-hyacinth), [pearls](https://thethinkingpress.org/materia-medica/pearls-prepared), and [coral](https://thethinkingpress.org/materia-medica/coral-red).

## What did the older authorities say?

**Hildegard of Bingen.** Gives a whole book of her *Physica* to the healing virtues of stones.

## Sources

- Hildegard of Bingen, *Physica*.
- Culpeper, N. (1653). *Pharmacopœia Londinensis*.
- Kunz, G. F. (1913). *The Curious Lore of Precious Stones*. Lippincott.
- Duffin, C. J. (2013). “Lithotherapeutical research sources from antiquity to the mid-eighteenth century,” in *A History of Geology and Medicine*. Geological Society.

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*The precious stones.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/precious-stones

Historical description, not medical advice.