Saturday, October 29, 2011

Agate Gems in Jewellery

     There so many types of Agate, found in many different places in the world, many people have a hard time discerning, and differentiating the different types. In this post I will try to show you just  few, that I have personally run across, and worked in to cabochons for jewellery making.
     Agate is a form of Chalcedony, and can be found across the world in many different colors, and in many places across the globe. Found primarily in a host rock of Volcanic nature, Agates may be found in many other stones as well. They have been used in stone carvings and in jewellery making for many centuries, from the ancient times to the current, and are very popular still today for these and many other uses.

A Mexican agate, showing only a single eye, has received the name of cyclops agate. Included matter of a green, golden, red, black or other color or combinations embedded in the chalcedony and disposed in filaments and other forms suggestive of vegetable growth, gives rise to dendritic or moss agate. Dendritic agates have fern like patterns in them formed due to the presence of manganese and iron oxides. Other types of included matter deposited during agate-building include sagenitic growths (radial mineral crystals) and chunks of entrapped detritus (such as sand, ash, or mud). Occasionally agate fills a void left by decomposed vegetative material such as a tree limb or root and is called limb cast agate due to its appearance.
Turritella agate is formed from silicified fossil Elimia tenera (erroneously considered Turritella) shells. E. tenera are spiral marine gastropods having elongated, spiral shells composed of many whorls. Similarly, coral, petrified wood and other organic remains or porous rocks can also become agatized. Agatized coral is often referred to as Petoskey stone or agate.
Greek agate is a name given to pale white to tan colored agate found in Sicily back to 400 B.C. The Greeks used it for making jewelry and beads. Even though the stone had been around centuries and was known to both the Sumerians and the Egyptians, both who used the gem for decoration and for playing important parts in their religious ceremonies, any agate of this color from Sicily, once an ancient Greek colony, is called Greek agate.
Another type of agate is Brazilian agate, which is found as sizable geodes of layered nodules. These occur in brownish tones interlayered with white and gray. Quartz forms within these nodules, creating a striking specimen when cut opposite the layered growth axis. It is often dyed in various colors for ornamental purposes.
Certain stones, when examined in thin sections by transmitted light, show a diffraction spectrum due to the extreme delicacy of the successive bands, whence they are termed rainbow agates. Often agate coexists with layers or masses of opal, jasper or crystalline quartz due to ambient variations during the formation process.
Other forms of agate include Lake Superior agate, carnelian agate (usually exhibiting reddish hues), Botswana agate, Ellensburg blue agate,

blue lace agate, plume agates, tube agate (with visible flow channels), fortification agate (which exhibit little or no layered structure), fire agate (which seems to glow internally like an opal) and Mexican crazy-lace agate (which exhibits an often brightly colored, complex banded pattern) also called Rodeo Agate and Rosetta Stone depending on who owned the mine at the time.

     Just a handful of the different types of Agate to be found all over the world , but because of their ability to take an extremely high polish, they are one of the most popular stones among rock & gem cutters to work with. Lake Superior Agates are among the hardest of the agate group, taking on a very impressive shine, making gem quality one of the highest available in the agate world. If you are looking for a durable, and very attractive stone, agate is the way to go, no matter what type, or color you choose, these stones are just some of the best available. Some are naturally colored, as in the Laguna agate, which can be found in colors like orange, yellow, red, pink, and purple.....others, like the ever popular Brazillian agate, might be dyed, using a heat process. (DO NOT try this unless you do extensive research in the how to)

ALL agates can be toxic when cutting them,so make sure this is done in water for safety reasons. For more information on cutting and polishing stone, visit .