Onyx is a type of natural stone that has been used for thousands of years for both decorative and functional purposes. But what exactly is onyx and how is it formed?
Onyx is a variety of chalcedony, which is a cryptocrystalline form of silica. More specifically, onyx refers to the parallel banded variety of chalcedony. This banding pattern occurs when silica deposits build up in layers on top of each other. The colors of the bands range from black and white to reddish-brown and beige.
Onyx forms when silica-rich liquids inside the earth permeate into gas bubbles inside lava. As the gas bubbles cool, the silica hardens into bands. The different colors result from the various impurities present when the silica bands form. For instance, iron and carbon result in black and white bands.
Onyx deposits are found in regions with volcanic activity, notably Brazil, Uruguay, India, Madagascar, Mexico, and the United States. The largest onyx quarry is located in Tecali de Herrera, Mexico. This quarry produces onyx slabs that are exported worldwide for use in everything from jewelry to architecture.
Onyx has been used by humans for thousands of years, dating back to ancient Egypt. The Egyptians carved onyx into bowls, vases, and figurines. Black onyx was often used alongside gold in ancient Egyptian art for contrast and was thought to symbolize regeneration and rebirth due to the flesh-like color of the stone.
The Romans also used onyx decoratively. When holding gladiator games, the Romans would carve decreases on onyx to commemorate victories. Roman poets also wrote about cups carved from onyx as extravagant items only used by the wealthy.
Today, onyx remains a popular natural stone utilized for decorative purposes like sculptures, carvings, countertops, sinks, and tiles. It is also frequently used to make cabochons, beads, and tumbled stones for jewelry. Black onyx, in particular, remains a common material in men's accessories, like tuxedo studs and cufflinks.
While cultured onyx does exist today, true natural onyx is still highly valued as a gemstone. Onyx rates at 6.5-7 on the Mohs hardness scale, making it suitable for both jewelry pieces and architectural details.
The swirling black and white patterns and bands make onyx a mesmerizing natural stone. Onyx can only achieve its unique aesthetic through the natural process of silica deposits forming layered bands over time. So while cultured onyx imitates the look of the natural stone, true onyx will always remain a prized natural material. Its long history of decorative use across ancient civilizations and striking visual appearance confirm that onyx is indeed a treasured natural stone.
