Sardonyx

Sardonyx is a reddish stone called a sard mixed with white, banded chalcedony and is composed of crystalline silicon dioxide. Like quartz, the polished sardonyx has a glassy finish. The black and/or white banding known as onyx has the same composition of silicon dioxide. One component cannot be more durable than the other. Sardonyx by having a standard hardness is therefore weather resistant because all three components are made of the same material, vitreous sand. By coincidence, the process of fossilization in petrified wood includes quartz crystal like sardonyx. One might even conclude the color variations of the finished product are due to the balance of materials inside the stone. The chalcedony has a fleshy tone according to Albertus Magnus who described its color as similar to a fingernail. The mixture of alternating colors adds to the mineral’s beauty with flowlines and varying degrees of transparency. Albertus Magnus was curious if the sard acted as a matrix. In his writing, he said the matrix of a stone acted like a house where the mineral forms. The fluid like structures of red and white layers resemble those of other groups of minerals formed deep inside caves. Such layering is a feature ideal for displays. Although sardonyx is August’s original birthstone, it’s infrequently found in jewelry shops since the alternative birthstones are better suited for jewelry. Compared to spinel and peridot, sardonyx also known as banded agate is thought to be less attractive for regular wear. That opinion, however, was not always the case. In ancient times, sardonyx was exceptionally valuable and made into rings for Roman soldiers.

When the sard lays over carnelian, the tone of the stone is said to change because one has a deep reddish color while the other has an orange color. The minerals both are chemically indistinguishable. Without the bands of onyx, sardonyx so closely resembles carnelian both were thought to be the same stone until the Middle Ages. According to George Kunz, the Greek Septuagint and Latin Vulgaris used the ancient word sardius for carnelian, whereas the word chenem was used by the Egyptians for all red stones including red jasper. Had sarcasm worked its way into the Medieval text? Maybe. Carnelian and sardonyx are known as members of the chalcedony family. The name sard appears to be a metonym for the Latin “sarda” penned by Pliny the Elder meaning “from Sardis”. The matter becomes more complex in the tenth century when sardius is used for “flesh-colored”. A translator’s footnote in the Book Of Minerals has an explanation about the inclusion of red jasper, an opaque variety of chalcedony, in regard to the section on sardonyx. The virtue of it without onyx was believed to be the improvement of one’s wits.

Artists sometimes take advantage of the banding to make bas relief. Utilizing a phenomenon known by us as pareidolia. images emerged by nature out of the stone and was thought to be magic. Geometry can also be utilized in the making of magic. The tumbled variety of sardonyx can be carved by a lapidary into regular polyhedra — tough and durable —such as cubes and octagons. Lastly, the configuration of amethyst and sardonyx over the navel talk volumes as to the use of stones as healing crystals during the late-Middle Ages:


Furthermore, Diascorides and Aristotle say that amethyst

and sardines placed or suspended over the navel of a man

is drunk or is drinking wine, oppose the fumes of wine and

cure drunkenness freeing him from an attack.

— Albertus Magnus, Book Of Minerals


Sardonyx was originally mined in Arabia as well as in India, both being places where finer specimens are found; furthermore, sardonyx can also be mined in Germany as well as Tyrol. Sardonyx can take on a high polish which made this mineral good for engravers. The Ptolemy Cameo was made out of sardonyx in the image of Alexander the Great. The power of the stone came from the believe that it made the bearer modest. The Ancient Romans believed a sardonyx would increase in quality if suitably engraved into a talisman. This last point being the case because differing layers offer a variety of effects called virtues.


Sardonyx […] is a stone compounded of the Sardius and

Onyx and very often also of the Chalcedonius. Sometimes

it is distinguished with three colors, black, Chalcedonian, and

Sardian; and the more distinct the colors are, so much better

is the Sardonyx.

— Camillius Leonardus, Mirror Of Stones


Sardonyx was frequently engraved with the image of Mars on the front or of Hercules in the ancient world. The virtue of Mars was fearlessness, while the virtue of Hercules was courage. It was also believed although in later times that the sardonyx shared the same virtues of agates in protecting the wearer from venomous bites and infections. As an amulet, sardonyx gave the wearer self-control and the ability to attract friends. Camillius Leonardus said it placed restraint on those inclined to dissipation. As a gift, engraved sardonyx made an agreeable companion.


  • Albert Magnus (1193-1280) was instructed in the writings of Aristotle before taking-on orders. He became a Dominican about the year 1223 and studied theology. As a Master of Theology, he was able to become a professor at the University of Paris where Thomas Aquinas studied under him. Of the many topics that were included in Albert Magnus’s writings; astrology, mineralogy, and alchemy were part of a corpus on natural sciences. For the most part, he became known as a magician after his death for his study of alchemy.

  • Camillus Leonardus (1451 – 1550) was an Italian astronomer, mineralogist, and physician. Although the topics of his works mainly deal with the occult power of gems and their engraved images, he also created astronomical tables verifying the position of fixed stars and published astrological rules for the administration of drugs.

  • Pliny the Elder (23 AD – 79) was an Italian historian who died near Pompeii in 79AD. His books on natural history were used throughout the Middle Ages as a reference and compilation of knowledge. As Western science emerged from the medieval period, mistakes were discovered in his compiling of information, and these were based on errors in reading original authors. His Natural History has since been credited as the first encyclopedia.