Minerals & Gemstone 480x104

Advertising Information

Lavendar Blue Chalcedony

The Gemstone Chalcedony

Chalcedony is the form of Quartz that is compact and microcrystalline. It occurs in many different forms, colors, and patterns, and many varieties have been used as gemstones since antiquity. In the gemstone trade, the term Chalcedony is often used specifically to describe the white, gray, or blue translucent type of Chalcedony, but its technical term includes all additional varieties.
Chemical Formula SiO2
Color White, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Black, Banded, Multicolored
Hardness 6.5 - 7
Crystal System Hexagonal
Refractive Index 1.54 - 1.55
SG 2.63 - 2.65
Transparency Translucent to opaque
Double Refraction .009
Luster Vitreous to waxy
Cleavage None
Mineral Class Quartz (Chalcedony)

Chalcedony AUCTIONS

Chalcedony is found in all types of colors, and its varieties are named based on color. The variety Agate is a multicolored form, well known for its distinctive banding patterns. Some forms of Chalcedony, such as Chrysoprase, are intensely colored, while others are light. In blue Chalcedony, the deeper the color, the more desirable the gemstone. The classic Chalcedony varieties are described below:

Multicolored banded variety, and the most well-known and unique form of Chalcedony. Agate itself has many different known varieties. All Agates contain distinctive patterns, which make each Agate different from the next. See the Agate gemstone page for more details.

Opaque, compact form, most often green in color, containing small Mica, Hematite, or Goethite scales which cause a glistening effect. See the Aventurine gemstone page for more details.

Dark green to greenish blue variety speckled with red or brown spots. See the Bloodstone gemstone page for more details.

Red to amber-red translucent variety. Some forms of Carnelian are heat treated to darken the lighter tones. See the Carnelian gemstone page for more details.

Apple green variety; one of the more popular gemstone forms of Chalcedony. See the Chrysoprase gemstone page for more details.

Opaque form of brown, often multicolored, spotted, or speckled. See the Jasper gemstone page for more details.

May describe solid black Chalcedony, banded black and white Chalcedony (usually in parallel banding), or any Chalcedony with a black base and white upper layer. See the Onyx gemstone page for more details.

Sard and Sardonyx
Sard is the brownish to brownish-red, transparent to translucent variety. The related Sardonyx has parallel bands of brownish to red alternating with white or sometimes black bands.

Tiger's Eye
Pseudomorph of compact Quartz after the fibrous mineral Crocidolite. Tiger's Eye is famous for its chatoyant effect and glistening sheen. See the Tiger's Eye gemstone page for more details.

Chalcedony is the source of a host of different gemstones. Most gem forms are polished as cabochons and beads for use in bracelets, necklaces, earrings, and as costume jewelery. They are also used as animal carvings and cameos. Besides for all the named varieties that are used as gems, the translucent gray and blue forms of Chalcedony have recently gained much popularity.

Varieties specific to Agate, Jasper, Onyx, and Tiger's Eye are listed separately.

Chalcedony is sometimes dyed to create more vibrant colors. This is especially true of vivid blue, red, and pink colors. White Chalcedony is also occasionally dyed light blue to resemble natural blue Chalcedony.

Chalcedony SOURCES
Chalcedony is abundant and found worldwide, with individual sources too numerous to mention.

Most of the Chalcedony gemstones are unique in color and style, and can be easily distinguished from most other gemstones. Some forms of Opal may resemble Chalcedony, but Opal lacks the hardness of Chalcedony.

Chalcedony PHOTOS [Click photos for more details]
Additional images for the varieties Agate, Aventurine, Bloodstone, Carnelian, Chrysoprase, Jasper, Onyx, and Tiger's Eye are listed separately.

Chalcedony IN THE ROUGH PHOTOS [Click photos for more details]

DISCUSSIONView Forum | Post to Forum
Have a question about Chalcedony? Visit our Q&A Community and ask the experts!

To sponsor this page, click here.
Let us know how we can update this page
(Click for more details)
We strive for accurate content and locality information. If you feel any of the content is incorrect, or if you feel we are missing vital locality information, please fill out the form below so we can update the site. If you are requesting a locality be added, please only include significant locality occurences for the mineral.