Gemstones, Diamonds, Pearls -
My Shopping Cart My Account Gem Library
|Welcome to|Single Stones|Calibrated Stones|Pairs|Mix Lots|Closeouts|Carved Gems|lapidary and gemological tools and supplies|Gem Smart Search|
 Home / Gem Library / Natural Gemstones / Chalcedony June 10, 2023  

Natural Chalcedony
E-mail this article to a friend

There are 49 Chalcedony(s) available at

The name chalcedony is applied to any fine grained quartz with a fibrous or crypto- crystalline microstructure. It often displays some kind of distinctive banding. The name agate is used for the sub variety of chalcedony which displays distinctive banding with successive layers differing in color and degree of translucency.

Known Facts
Color Key: grayish, purple, white, green, blue, lavender, yellow, brown.
Refractive Index: 1.530 - 1.539
Chemical Composition: SiO2
Hardness: 6.5
Density: 2.57 2.64
Crystal Group: Hexagonal
Ocurrence: Brazil, U.SA. Germany, India, Uruguay, Austarlia, Egypt, Italy, Scotland, South Africa, Namibia, Madagascar, Mexico, Tanzania, and many other localities throughout the world.

The individual fibers of chalcedony and its subvarieties are not physically separable; they occur as parallel or near parallel aggregates or as spherules. The fiber direction is perpendicular to the layering while the banding is parallel to the free surface or cavity in which the chalcedony occurs.

The hardness of chalcedony is variable around 6.5; somewhat lower than that of more coarsely crystallized quartz which has a hardness of 7. The specific gravity also varies according to porosity, water content, and the presence of other substances. The normal range is 2.57 2.64. Chalcedony is about 90 99% SiO2. Brown and reddish varieties are higher in Fe2O3.

Chalcedony fractures easily across the banding to give a splintery surface with a waxy luster. Most chalcedony is somewhat pale and grayish in appearance.

Chalcedony is deposited in a variety of environments and deposition is commonly at low temperatures. Light colored material is often found as a late hydrothermal deposit or an alteration product in acidic or basic igneous rocks, tuffs and breccias. It is very common as crusts of vein or cavity fillings.

The most prized of the chalcedonies are the translucent green stones known as chrysoprase and the brown iridescent and colorful stones known as fire agates. Other important kinds of chalcedony include bloodstone, lace agate, sard, iris agate, onyx, and carnelian.

Chalcedony Chalcedony Chalcedony Chalcedony
Check our Top, Largest, Smallest or Latest Chalcedony's.

Chalcedony Stats/
Popularity Index: 960596hits
Total Items: 49items
Total Weight: CTS 1961.67
Cheapest: USD 2.06
Most Expensive: USD 90.88
Largest: CTS 59.25
Smallest: CTS 1.36
Last Added: 01/12/15 03:04:42

Knowledge Search/
Enter Keywords:
Enter one or more keywords (i.e madagascar sapphires ).

About Gemstones /

Gem Library/
Gems Legend and  Lore Gems Legend and Lore
Some of the latest of ways that gems have been associated with Birthstones and Signs of the Zodiac.
Understanding Gemstones Understanding Gemstones
Learn about Physical and Optical properties, color, clarity and cut of gemstones.
Gems Glossary Gems Glossary
Ever wonder what are "Blemish", "Luster", "Saturation" "Uniformity" or "Mine Run" means?
Reference and  Links Reference and Links
Recommended books and links to Gem, Jewelry&Mineral Magazines, Gem Institutes and Labs.

Book’s Corner/
Buy at Ruby & Sapphire by Richard W. Hughes
Price: USD 98.00
"This book is surely the best study ever done on the exotic subject of rubies and sapphires..."
see more recommendations

 Top of Page Need help?  

Gemstones for sale: Alexandrite, Garnet, Diamond, Opal, Spinel, Sapphire, Tourmaline, Tanzanite, Tsavorite,
Gemstones by Category: Calibrated, Carving, Closeout, Jewelry, Mixed Lot, Pair, Rough, Single, Best Sellers or Featured Gemstones.
Gemstone education: Colored Gemstones Guide, Gems Library, Gemstone Treatments, Gemstone Glossary, Gems and Astrology,

All Transactions secure by Thawte certificate - click here to validate Ebay Power Seller Gem Certification Various Shipping Options Major Credit Cards Accepted

All trademarks and logos shown herein are the property of their respective owners. © Copyright, 1998-2011. All rights reserved. Use of this site constitutes acceptance of Return Policy, Privacy Policy and Trading Guarantee. Published and operated by David Wein Ltd. 32 Hollywood Road, Central, Hong Kong Island Hong Kong. Lost? Check site map or resources page.

Site design and maintenance by NetComposite ®.