Onyx

Onyx is a pretty stone with stripes.

These stripes can be black and white. Some stones have red or brown stripes too.

People use these stones to make beads. They also use them to make jewelry. Long ago, people in Egypt made bowls from it. Some people thought the red stone gave them courage. It is a very special stone to see.

Onyx is a type of stone called agate.

It has stripes that run in straight lines. These stripes are often black and white. Some stones have red or brown stripes. We call these red stones sardonyx.

Onyx is made of tiny parts of quartz. It is very hard. People use it for jewelry and beads. They also carve it into art. In ancient Rome, people made gems called cameos. A cameo uses the stone's layers to make a picture.

One famous Roman cameo is the Gemma Augustea.

Many stones are sold as black onyx. But most are not natural. People use dyes to change the color. They may soak the stone in sugar. Then they use acid to make it dark. This has been done since Roman times. Many people also sell soft stones as onyx. These are actually made of calcite. True onyx can be found in many places. It is in Mexico, Greece, and Brazil. It is also in the United States.

Onyx is a special kind of agate. It is a silicate mineral with beautiful stripes. Most people know it for its black and white bands. These bands run in straight, parallel lines. Sometimes the colors are just light and dark. There is also a type called sardonyx. This version has red or brown bands mixed with black or white.

Onyx is important because of its unique look. Its stripes make it great for art and jewelry.

This stone forms through a specific way it works. It is made of chalcedony bands in different colors. These bands are parallel to each other. The stone is cryptocrystalline. This means it is made of very fine intergrowths. It uses two silica minerals called quartz and moganite.

Because the bands are so straight, it looks very neat. This is different from other agates that have messy patterns. The structure of the stone creates its famous striped appearance.

People have used onyx for a very long time. Ancient Egyptians used it during the Second Dynasty. They made things like bowls and pottery. The ancient Greeks and Romans also knew about it. A famous naturalist named Pliny the Elder lived in the first century. He wrote about onyx in his book, Naturalis Historia. He even described how to change the color of stones.

This shows that people have been interested in onyx for thousands of years.

Onyx is found in many parts of the world. You can find it in Mexico, Greece, and Brazil. It is also in the US, China, and India. Many items sold as black onyx are actually treated. People soak chalcedony in sugar solutions to change it. Then they use acid to turn the sugar dark. This makes the stone look black. Most black onyx on the market today is made this way.

Many people also sell soft calcite as onyx.

Onyx has many links to history and culture. Romans carried sardonyx amulets into battle for courage. In the Renaissance, people thought it helped them speak well. Some people in Persia thought it helped with epilepsy. In England, midwives used it during childbirth. Architects have used it too. Mies van der Rohe used onyx slabs in a villa in 1930. These slabs made a shimmering wall in the building.

Onyx is a specific variety of agate, which is a type of silicate mineral. It is most famous for its beautiful, parallel bands of color. While many agates have messy or swirling patterns, onyx is defined by its straight, level stripes. These stripes can be black and white, or they can be monochromatic with alternating light and dark tones.

Because of these striking visual patterns, onyx has been a highly valued material for jewelry and art for thousands of years. It is a member of the chalcedony family, a group of minerals known for their fine structure.

The physical makeup of onyx is quite complex. It is described as cryptocrystalline, which means it is composed of very fine intergrowths of minerals. Specifically, it consists of the silica minerals quartz and moganite. These minerals form the distinct chalcedony bands that create the stone's appearance. In true onyx, these colored bands run parallel to one another. This organized structure is what separates it from other types of agate that might have more chaotic or contorted banding.

There are different varieties of this mineral based on their color patterns. The most common is black onyx, which features black and white bands. Another important variety is sardonyx. In sardonyx, the colored bands are a shade called sard, which ranges from red to brown. These sard-colored layers alternate with black or white layers.

It is important to note that the term "onyx" is often used incorrectly. People sometimes call parallel-banded varieties of marble, calcite, obsidian, or opal "onyx," even though those materials are not true silicate minerals.

Humans have interacted with onyx for a very long time. As early as the Second Dynasty in Egypt, people used onyx to create pottery items and bowls. The ancient Greeks and Romans were also very familiar with the stone. A first-century naturalist named Pliny the Elder even wrote about onyx in his famous work, *Naturalis Historia*. He documented different types of onyx and the ways people could change their colors.

This long history shows how much people have admired the stone's unique properties.

Because natural black onyx is not very common, many stones are treated to look that way. Since ancient times, people have used artificial methods to produce black, red, or yellow colors. One method involves soaking chalcedony in sugar solutions. After the stone absorbs the sugar, it is treated with sulfuric or hydrochloric acid. This process carbonizes the sugars in the top layers of the stone, turning it dark.

Other treatments include using heat or nitric acid to remove colors that people do not like. Today, much of the "black onyx" found in stores is actually dyed or treated chalcedony.

Onyx has played many roles in different cultures throughout history. In ancient Rome, soldiers carried amulets made of sardonyx engraved with Mars, the god of war. They believed these charms would give them courage during battle. During the Renaissance in Europe, people thought wearing sardonyx could help them speak with eloquence. In Persian tradition, it was sometimes believed to help with epilepsy. Even in England, midwives used sardonyx during childbirth by placing it between the mother's breasts. These diverse beliefs show the deep cultural significance of the stone.

Beyond jewelry, onyx has been used in significant architectural and artistic works. In the 1920s and 1930s, Brazilian green onyx was used as bases for Art Deco sculptures. The sculptor Ferdinand Preiss used it for many of his chryselephantine works. In 1930, the architect Mies van der Rohe used slabs of onyx from the Atlas Mountains in the Villa Tugendhat. He used them to create a shimmering, semi-translucent interior wall.

Whether in a small ring or a large building, onyx continues to be a material that captures the imagination.