Stone Stories Part II: Chalcedony

This series is intended as a love letter to the inspiration of many of my jewelry designs: rocks. With a little spit and polish, even the most humble stone can become precious. Instead of merely using traditional gemstones, I hunt for stones that in some way are like no other. As I seek to design and create one-of-a-kind adornments, I'm looking for ways to reflect the unique personality of the wearer. For me the value in these materials is their singular beauty. I hope you enjoy learning a little more about the stones I use, why I use them, and (for those who like the science) a little more information on how and where these stones are formed.

Story Behind the Stone: Chalcedony

Why this stone?

Pronounced kal-SED-oh-nee, Chalcedony looks as though it has an inner light, a quiet glow that is never quenched. There is a magical quality to its soft luminosity. Chalcedony can be found in a lot of colors, but I'm drawn to the soft blues and purples, such as Holley blue which is found in Oregon (and is more purple than blue). This stone feels serenely and confidently feminine to me; it doesn't need to shout to be noticed. I imagine that the woman who wears this stone doesn't feel the need to prove herself to anyone!  Chalcedony looks beautiful in both silver and gold. I think it lends itself to most designs and adds a touch of elegance.

This is one of those matriarchal stones that is related to so many others it's hard to know where one ends and the other begins. Technically, lots of stones are Chalcedony--agate, jasper, carnelian, onyx, the list goes on. So how do you tell the difference? That is a hard question to answer. Generally, this material starts to get sub-categorized by color, pattern, and diaphaneity (I just learned this word while researching). Diaphaneity refers to the way light interacts with the surface of a stone; a stone can be transparent--as in the case of some clear quartz, translucent (or diaphanous)--as in agate where the light passes through but is distorted, or opaque--as in jasper where the light does not pass through at all.

So while agate is a form of chalcedony, it is typically characterized by its translucency, while jasper, also chalcedony, is usually opaque. At the end of the day it comes down to mineral composition and structure, which for my purposes is way besides the point.

In my experience buying stones and learning about them in the "trade" (the jewelry industry) many of the names associated with stones are partly a marketing technique and one stone can have many different names. When buying chalcedony certain characteristics come to mind: a pure color not broken up by banding or patterns (unless subtle and monochromatic), and transparency, so not at all like jasper (even though jasper is a form of chalcedony--confused yet?)

Where it is found

Chalcedony is common and can be found all over the world. The most notable locations are Brazil, Madagascar, Mexico, and the US. It appears in a wide range of colors and hues, from white and gray, to blue, yellow, pink, purple and red. The most highly prized forms of chalcedony are gem quality that show a glowing translucence.

How it is formed

Chalcedony is a form of cryptocrystalline silica, meaning that the crystalline structure of the stone is invisible to the naked eye. Part of the quartz family, chalcedony is formed in water-rich environments where silica-rich minerals dissolve and are deposited into the cavities and fractures in rocks, and geodes. 

The chemistry of the water in which the silica has dissolved has an effect on the color and texture of the stone. Acidic water may cause yellow or orange coloration, while alkaline water may cause blue or gray color. Temperature, pressure and time also effect the formation and texture of this stone. As with all stones, the presence of other minerals also effect the color. Iron oxide can cause an orange or red color, while manganese causes purple or pink hues.

You can find more examples of my work featuring chalcedony in my Intertwined collection.