Chalcedony Stone: Properties, Benefits & Meanings

What Is Chalcedony?

Chalcedony (kal-sed-n-ee, kal-suh-doh-nee) is a form of microcrystalline quartz that is composed of fine, intergrown crystals of quartz and moganite. The crystals are usually so small that they can only be seen with a microscope.

In common trade, only the translucent, single-color types are usually classified as “chalcedony,” while the others are referred to under various names such as agate, chrysoprase, bloodstone, onyx, or jasper.

where does Chalcedony’s name originate from?

The word “chalcedony” comes from the Greek word “chalcedonios” which means “of Chalcedon.” This is likely a reference to Chalcedon, an ancient maritime town located in what is now Turkey.

Chalcedony was first described by Pliny, the Elder, a Roman naturalist, in his Naturalis Historiae, written around 77 AD.

What are the Physical Properties of Chalcedony?

Chalcedony is a gemstone that has a hardness of 6.5-7 on the Mohs scale. This makes it an ideal stone for crafting jewelry and other decorative items.

Chalcedony is a translucent, cryptocrystalline variety of quartz. As such, it shares many of the same physical properties as other types of quartz.

Chalcedony typically has a waxy luster and is translucent to opaque. It has a lower density than other quartz varieties (SG: 2.58–2.64). It is porous and can be stained to improve the color.

Mineral Group	Quartz
Formula	SiO2
Chemical name	Silicon dioxide
Color	white, blue, gray, colorless, multicolored
Hardness (Mohs scale)	6.5 – 7
Toughness	Good
Fracture	conchoidal, uneven
Luster	vitreous to waxy
Specific Gravity	2.55-2.91
Transparency	Transparent to opaque

Where is Chalcedony Found?

Chalcedony is found in a variety of places around the world. It is most commonly found in Europe, Africa, and North America.

List of major chalcedony deposits by country:

What Color is Chalcedony?

Pure chalcedony is white. However, it can also be found in a wide range of colors, including shades of blue, green, yellow, purple, pink, and gray. The color is caused by the presence of trace elements in the crystal structure. For example, manganese gives chalcedony a pink or purple hue, while iron oxides can give it a red or yellow hue.

Popular varieties of chalcedony based on their distinct colors:

Types of Chalcedony

Mineralogists know more than a hundred varieties of chalcedony, differing in composition, structure, and shade. But only a few dozen of them are used in jewelry and are of high value.

The varieties of chalcedony most commonly found in jewelry are:

Varieties	Colors
Agate	Multicolored banded variety is characterized by color bands in a concentric form or moss-like inclusions.
Carnelian	Translucent to semiopaque, reddish-orange to a deep burgundy color
Sard	Chalcedony with a reddish-brown hue and streaks of black
Chrysoprase	A clear quartz variety that ranges in color from pale apple green to blue-green, depending on the amount of manganese present
Bloodstone	Dark red to maroon in color, typically banded or spotted
Onyx	Banded black with a metallic sheen, often cut into geometric or animal forms
Jasper	Shades of brown, yellow, red, and green
Petrified Wood	Colorful agate that has replaced tree trunks and limbs
Chrome Chalcedony	A translucent, chromium-green variety of chalcedony similar to chrysoprase from Zimbabwe, Africa
Chalcedonyx	alternating strips or bands of gray and white
Sardonyx	a variety of chalcedony with a blue-green hue and black inclusions

What Is Chalcedony Used For?

Chalcedonies of all varieties have been used in jewelry and gemstone carvings since ancient times. The earliest stone tools were commonly made of some form of chalcedony.

Uses Of Chalcedony in History

• The Egyptians used chalcedony as a building material, especially for temples and tombs.
• The Greeks used it in facial masks to cure diseases of the eyes, ears, and skin.
• Hieroglyphs in Ancient Egypt depicted a chalcedony ring on the hand of Ahmose Nefertari, the consort of Akhenaten.
• In the Middle Ages, it was used in the manufacture of agate buttons, combs, and bottles for perfume.
• The Egyptians used chalcedony to make glass. They believed that chalcedony brought eternal youth, so it gave their glass its green color.
• Chalcedony was popular in Victorian jewelry and ornaments.
• Chalcedony was a highly prized gem by ancient priests. It was a sacred material with lots of symbolism.
• It was a prominent stone in religious objects such as the chalice, the saint’s organ, the papal tiara, and baptismal fonts.
• It was commonly used to make crosses and crucifixes.

Uses Of Chalcedony In Modern Times

Modern uses of chalcedony are mainly related to its uses in the production of jewelry, figurines, utensils, and artistic objects, as well as scientific instruments, such as optical prisms.

Chalcedony Value and Price

Chalcedony can be a very affordable stone. However, location, color, size, and finish can greatly affect its value. Chalcedony prices range from a few dollars per carat to hundreds of dollars per carat. The most valuable colors are in the purple and blue-violet range.

The price of chalcedony is affected by:

1. Location: Some locations are known for their high-quality chalcedony specimens. These specimens command premium prices.
2. Color: Chalcedony occurs in many colors. However, the most valuable colors are in the purple and blue-violet range.
3. Size: Large specimens are rare and command very high prices. Specimens with unusual shapes or patterns also command higher prices.
4. Clarity: Most chalcedony is opaque and does not contain many smaller crystals. Specimens with clear areas or that contain large numbers of smaller crystals command higher prices.
5. Finish: The finish on chalcedony specimens affects their price. Specimens that have been polished to a high-luster finish command higher prices.